diff --git a/README.md b/README.md
index 66e8e69..14cad04 100644
--- a/README.md
+++ b/README.md
@@ -43,6 +43,9 @@ local opts = {
   show_relative_numbers = false,
   show_symbol_details = true,
   preview_bg_highlight = 'Pmenu',
+  autofold_depth = nil,
+  auto_unfold_hover = true,
+  fold_markers = { '', '' },
   keymaps = { -- These keymaps can be a string or a table for multiple keys
     close = {"<Esc>", "q"},
     goto_location = "<Cr>",
@@ -51,6 +54,11 @@ local opts = {
     toggle_preview = "K",
     rename_symbol = "r",
     code_actions = "a",
+    fold = "h",
+    unfold = "l",
+    fold_all = "W",
+    unfold_all = "E",
+    fold_reset = "R",
   },
   lsp_blacklist = {},
   symbol_blacklist = {},
@@ -103,6 +111,9 @@ local opts = {
 | symbols                | Icon and highlight config for symbol icons                                     | table (dictionary) | scroll up                |
 | lsp_blacklist          | Which lsp clients to ignore                                                    | table (array)      | {}                       |
 | symbol_blacklist       | Which symbols to ignore ([possible values](./lua/symbols-outline/symbols.lua)) | table (array)      | {}                       |
+| autofold_depth         | Depth past which nodes will be folded by default                               | int                | nil                      |
+| auto_unfold_hover      | Automatically unfold hovered symbol                                            | boolean            | true                     |
+| fold_markers           | Markers to denote foldable symbol's status                                     | table (array)      | { '', '' }         |
 
 ## Commands
 
@@ -123,6 +134,11 @@ local opts = {
 | K          | Toggles the current symbol preview                 |
 | r          | Rename symbol                                      |
 | a          | Code actions                                       |
+| h          | Unfold symbol                                      |
+| l          | Fold symbol                                        |
+| W          | Fold all symbols                                   |
+| E          | Unfold all symbols                                 |
+| R          | Reset all folding                                  |
 | ?          | Show help message                                  |
 
 ## Highlights
diff --git a/lua/symbols-outline.lua b/lua/symbols-outline.lua
index 816ee1b..09a5823 100644
--- a/lua/symbols-outline.lua
+++ b/lua/symbols-outline.lua
@@ -5,11 +5,14 @@ local writer = require 'symbols-outline.writer'
 local config = require 'symbols-outline.config'
 local utils = require 'symbols-outline.utils.init'
 local View = require 'symbols-outline.view'
+local folding = require 'symbols-outline.folding'
 
 local M = {}
 
 local function setup_global_autocmd()
-  if config.options.highlight_hovered_item then
+  if
+    config.options.highlight_hovered_item or config.options.auto_unfold_hover
+  then
     vim.api.nvim_create_autocmd('CursorHold', {
       pattern = '*',
       callback = function()
@@ -63,6 +66,18 @@ local function wipe_state()
   M.state = { outline_items = {}, flattened_outline_items = {}, code_win = 0 }
 end
 
+local function _update_lines()
+  M.state.flattened_outline_items = parser.flatten(M.state.outline_items)
+  writer.parse_and_write(M.view.bufnr, M.state.flattened_outline_items)
+end
+
+local function _merge_items(items)
+  utils.merge_items_rec(
+    { children = items },
+    { children = M.state.outline_items }
+  )
+end
+
 local function __refresh()
   if M.view:is_open() then
     local function refresh_handler(response)
@@ -71,12 +86,11 @@ local function __refresh()
       end
 
       local items = parser.parse(response)
+      _merge_items(items)
 
       M.state.code_win = vim.api.nvim_get_current_win()
-      M.state.outline_items = items
-      M.state.flattened_outline_items = parser.flatten(items)
 
-      writer.parse_and_write(M.view.bufnr, M.state.flattened_outline_items)
+      _update_lines()
     end
 
     providers.request_symbols(refresh_handler)
@@ -85,9 +99,13 @@ end
 
 M._refresh = utils.debounce(__refresh, 100)
 
-local function goto_location(change_focus)
+function M._current_node()
   local current_line = vim.api.nvim_win_get_cursor(M.view.winnr)[1]
-  local node = M.state.flattened_outline_items[current_line]
+  return M.state.flattened_outline_items[current_line]
+end
+
+local function goto_location(change_focus)
+  local node = M._current_node()
   vim.api.nvim_win_set_cursor(
     M.state.code_win,
     { node.line + 1, node.character }
@@ -100,6 +118,45 @@ local function goto_location(change_focus)
   end
 end
 
+function M._set_folded(folded, move_cursor, node_index)
+  local node = M.state.flattened_outline_items[node_index] or M._current_node()
+  local changed = (folded ~= folding.is_folded(node))
+
+  if folding.is_foldable(node) and changed then
+    node.folded = folded
+
+    if move_cursor then
+      vim.api.nvim_win_set_cursor(M.view.winnr, { node_index, 0 })
+    end
+
+    _update_lines()
+  elseif node.parent then
+    local parent_node =
+      M.state.flattened_outline_items[node.parent.line_in_outline]
+
+    if parent_node then
+      M._set_folded(
+        folded,
+        not parent_node.folded and folded,
+        parent_node.line_in_outline
+      )
+    end
+  end
+end
+
+function M._set_all_folded(folded, nodes)
+  nodes = nodes or M.state.outline_items
+
+  for _, node in ipairs(nodes) do
+    node.folded = folded
+    if node.children then
+      M._set_all_folded(folded, node.children)
+    end
+  end
+
+  _update_lines()
+end
+
 function M._highlight_current_item(winnr)
   local has_provider = providers.has_provider()
 
@@ -127,26 +184,31 @@ function M._highlight_current_item(winnr)
 
   local hovered_line = vim.api.nvim_win_get_cursor(win)[1] - 1
 
-  local nodes = {}
-  for index, value in ipairs(M.state.flattened_outline_items) do
+  local leaf_node = nil
+
+  local cb = function(value)
+    value.hovered = nil
+
     if
       value.line == hovered_line
       or (hovered_line > value.range_start and hovered_line < value.range_end)
     then
-      value.line_in_outline = index
-      table.insert(nodes, value)
+      value.hovered = true
+      leaf_node = value
     end
   end
 
-  -- clear old highlight
-  ui.clear_hover_highlight(M.view.bufnr)
-  for _, value in ipairs(nodes) do
-    ui.add_hover_highlight(
-      M.view.bufnr,
-      value.line_in_outline - 1,
-      value.depth * 2
-    )
-    vim.api.nvim_win_set_cursor(M.view.winnr, { value.line_in_outline, 1 })
+  utils.items_dfs(cb, M.state.outline_items)
+
+  _update_lines()
+
+  if leaf_node then
+    for index, node in ipairs(M.state.flattened_outline_items) do
+      if node == leaf_node then
+        vim.api.nvim_win_set_cursor(M.view.winnr, { index, 1 })
+        break
+      end
+    end
   end
 end
 
@@ -166,9 +228,12 @@ local function setup_keymaps(bufnr)
   map(
     config.options.keymaps.hover_symbol,
     require('symbols-outline.hover').show_hover
-  )   
+  )
   -- preview symbol
- map(config.options.keymaps.toggle_preview, require('symbols-outline.preview').toggle)
+  map(
+    config.options.keymaps.toggle_preview,
+    require('symbols-outline.preview').toggle
+  )
   -- rename symbol
   map(
     config.options.keymaps.rename_symbol,
@@ -188,6 +253,26 @@ local function setup_keymaps(bufnr)
   map(config.options.keymaps.close, function()
     M.view:close()
   end)
+  -- fold selection
+  map(config.options.keymaps.fold, function()
+    M._set_folded(true)
+  end)
+  -- unfold selection
+  map(config.options.keymaps.unfold, function()
+    M._set_folded(false)
+  end)
+  -- fold all
+  map(config.options.keymaps.fold_all, function()
+    M._set_all_folded(true)
+  end)
+  -- unfold all
+  map(config.options.keymaps.unfold_all, function()
+    M._set_all_folded(false)
+  end)
+  -- fold reset
+  map(config.options.keymaps.fold_reset, function()
+    M._set_all_folded(nil)
+  end)
 end
 
 local function handler(response)
diff --git a/lua/symbols-outline/config.lua b/lua/symbols-outline/config.lua
index 5376b91..e5ed735 100644
--- a/lua/symbols-outline/config.lua
+++ b/lua/symbols-outline/config.lua
@@ -16,6 +16,9 @@ M.defaults = {
   show_symbol_details = true,
   preview_bg_highlight = 'Pmenu',
   winblend = 0,
+  autofold_depth = nil,
+  auto_unfold_hover = true,
+  fold_markers = { '', '' },
   keymaps = { -- These keymaps can be a string or a table for multiple keys
     close = { '<Esc>', 'q' },
     goto_location = '<Cr>',
@@ -25,6 +28,11 @@ M.defaults = {
     rename_symbol = 'r',
     code_actions = 'a',
     show_help = '?',
+    fold = 'h',
+    unfold = 'l',
+    fold_all = 'W',
+    unfold_all = 'E',
+    fold_reset = 'R',
   },
   lsp_blacklist = {},
   symbol_blacklist = {},
diff --git a/lua/symbols-outline/folding.lua b/lua/symbols-outline/folding.lua
new file mode 100644
index 0000000..df1626c
--- /dev/null
+++ b/lua/symbols-outline/folding.lua
@@ -0,0 +1,27 @@
+local M = {}
+local config = require 'symbols-outline.config'
+
+M.is_foldable = function(node)
+  return node.children and #node.children > 0
+end
+
+local get_default_folded = function(depth)
+  local fold_past = config.options.autofold_depth
+  if not fold_past then
+    return false
+  else
+    return depth >= fold_past
+  end
+end
+
+M.is_folded = function(node)
+  if node.folded ~= nil then
+    return node.folded
+  elseif node.hovered and config.options.auto_unfold_hover then
+    return false
+  else
+    return get_default_folded(node.depth)
+  end
+end
+
+return M
diff --git a/lua/symbols-outline/hover.lua b/lua/symbols-outline/hover.lua
index 27f2a01..cc75e81 100644
--- a/lua/symbols-outline/hover.lua
+++ b/lua/symbols-outline/hover.lua
@@ -25,7 +25,7 @@ function M.show_hover()
     hover_params.bufnr,
     'textDocument/hover',
     hover_params,
----@diagnostic disable-next-line: param-type-mismatch
+    ---@diagnostic disable-next-line: param-type-mismatch
     function(_, result, _, config)
       if not (result and result.contents) then
         -- return { 'No information available' }
diff --git a/lua/symbols-outline/parser.lua b/lua/symbols-outline/parser.lua
index 6be870a..fe2f8d1 100644
--- a/lua/symbols-outline/parser.lua
+++ b/lua/symbols-outline/parser.lua
@@ -2,6 +2,7 @@ local symbols = require 'symbols-outline.symbols'
 local ui = require 'symbols-outline.ui'
 local config = require 'symbols-outline.config'
 local t_utils = require 'symbols-outline.utils.table'
+local folding = require 'symbols-outline.folding'
 
 local M = {}
 
@@ -9,8 +10,9 @@ local M = {}
 ---@param result table The result from a language server.
 ---@param depth number? The current depth of the symbol in the hierarchy.
 ---@param hierarchy table? A table of booleans which tells if a symbols parent was the last in its group.
+---@param parent table? A reference to the current symbol's parent in the function's recursion
 ---@return table
-local function parse_result(result, depth, hierarchy)
+local function parse_result(result, depth, hierarchy, parent)
   local ret = {}
 
   for index, value in pairs(result) do
@@ -24,14 +26,6 @@ local function parse_result(result, depth, hierarchy)
       -- whether this node is the last in its group
       local isLast = index == #result
 
-      local children = nil
-      if value.children ~= nil then
-        -- copy by value because we dont want it messing with the hir table
-        local child_hir = t_utils.array_copy(hir)
-        table.insert(child_hir, isLast)
-        children = parse_result(value.children, level + 1, child_hir)
-      end
-
       -- support SymbolInformation[]
       -- https://microsoft.github.io/language-server-protocol/specification#textDocument_documentSymbol
       local selectionRange = value.selectionRange
@@ -44,7 +38,7 @@ local function parse_result(result, depth, hierarchy)
         range = value.location.range
       end
 
-      table.insert(ret, {
+      local node = {
         deprecated = value.deprecated,
         kind = value.kind,
         icon = symbols.icon_from_kind(value.kind),
@@ -54,11 +48,23 @@ local function parse_result(result, depth, hierarchy)
         character = selectionRange.start.character,
         range_start = range.start.line,
         range_end = range['end'].line,
-        children = children,
         depth = level,
         isLast = isLast,
         hierarchy = hir,
-      })
+        parent = parent,
+      }
+
+      table.insert(ret, node)
+
+      local children = nil
+      if value.children ~= nil then
+        -- copy by value because we dont want it messing with the hir table
+        local child_hir = t_utils.array_copy(hir)
+        table.insert(child_hir, isLast)
+        children = parse_result(value.children, level + 1, child_hir, node)
+      end
+
+      node.children = children
     end
   end
   return ret
@@ -139,14 +145,23 @@ function M.parse(response)
   return parse_result(sorted, nil, nil)
 end
 
-function M.flatten(outline_items, ret)
+function M.flatten(outline_items, ret, depth)
+  depth = depth or 1
   ret = ret or {}
   for _, value in ipairs(outline_items) do
     table.insert(ret, value)
-    if value.children ~= nil then
-      M.flatten(value.children, ret)
+    value.line_in_outline = #ret
+    if value.children ~= nil and not folding.is_folded(value) then
+      M.flatten(value.children, ret, depth + 1)
     end
   end
+
+  -- if depth == 1 then
+  --   for index, value in ipairs(ret) do
+  --     value.line_in_outline = index
+  --   end
+  -- end
+
   return ret
 end
 
@@ -155,7 +170,10 @@ function M.get_lines(flattened_outline_items)
   local hl_info = {}
 
   for node_line, node in ipairs(flattened_outline_items) do
-    local line = t_utils.str_to_table(string.rep(' ', node.depth))
+    local depth = node.depth
+    local marker_space = (config.options.fold_markers and 1) or 0
+
+    local line = t_utils.str_to_table(string.rep(' ', depth + marker_space))
     local running_length = 1
 
     local function add_guide_hl(from, to)
@@ -176,27 +194,46 @@ function M.get_lines(flattened_outline_items)
           -- i f index is last, add a bottom marker if current item is last,
           -- else add a middle marker
         elseif index == #line then
-          if node.isLast then
-            line[index] = ui.markers.bottom
+          -- add fold markers
+          if config.options.fold_markers and folding.is_foldable(node) then
+            if folding.is_folded(node) then
+              line[index] = config.options.fold_markers[1]
+            else
+              line[index] = config.options.fold_markers[2]
+            end
+
             add_guide_hl(
               running_length,
-              running_length + vim.fn.strlen(ui.markers.bottom) - 1
-            )
-          else
-            line[index] = ui.markers.middle
-            add_guide_hl(
-              running_length,
-              running_length + vim.fn.strlen(ui.markers.middle) - 1
+              running_length + vim.fn.strlen(line[index]) - 1
             )
+
+            -- the root level has no vertical markers
+          elseif depth > 1 then
+            if node.isLast then
+              line[index] = ui.markers.bottom
+              add_guide_hl(
+                running_length,
+                running_length + vim.fn.strlen(ui.markers.bottom) - 1
+              )
+            else
+              line[index] = ui.markers.middle
+              add_guide_hl(
+                running_length,
+                running_length + vim.fn.strlen(ui.markers.middle) - 1
+              )
+            end
           end
           -- else if the parent was not the last in its group, add a
           -- vertical marker because there are items under us and we need
           -- to point to those
-        elseif not node.hierarchy[index] then
-          line[index] = ui.markers.vertical
+        elseif not node.hierarchy[index] and depth > 1 then
+          line[index + marker_space] = ui.markers.vertical
           add_guide_hl(
-            running_length,
-            running_length + vim.fn.strlen(ui.markers.vertical) - 1
+            running_length - 1 + 2 * marker_space,
+            running_length
+              + vim.fn.strlen(ui.markers.vertical)
+              - 1
+              + 2 * marker_space
           )
         end
       end
@@ -216,6 +253,8 @@ function M.get_lines(flattened_outline_items)
     local hl_end = #string_prefix + #node.icon
     local hl_type = config.options.symbols[symbols.kinds[node.kind]].hl
     table.insert(hl_info, { node_line, hl_start, hl_end, hl_type })
+
+    node.prefix_length = #string_prefix + #node.icon + 1
   end
   return lines, hl_info
 end
diff --git a/lua/symbols-outline/providers/markdown.lua b/lua/symbols-outline/providers/markdown.lua
index 1123425..b1ffba3 100644
--- a/lua/symbols-outline/providers/markdown.lua
+++ b/lua/symbols-outline/providers/markdown.lua
@@ -8,15 +8,12 @@ function M.should_use_provider(bufnr)
 end
 
 function M.hover_info(_, _, on_info)
-  on_info(
-    nil,
-    {
-      contents = {
-        kind = 'markdown',
-        contents = { 'No extra information availaible!' },
-      },
-    }
-  )
+  on_info(nil, {
+    contents = {
+      kind = 'markdown',
+      contents = { 'No extra information availaible!' },
+    },
+  })
 end
 
 ---@param on_symbols function
diff --git a/lua/symbols-outline/providers/nvim-lsp.lua b/lua/symbols-outline/providers/nvim-lsp.lua
index cd2c544..a067872 100644
--- a/lua/symbols-outline/providers/nvim-lsp.lua
+++ b/lua/symbols-outline/providers/nvim-lsp.lua
@@ -23,15 +23,12 @@ function M.hover_info(bufnr, params, on_info)
   end
 
   if not used_client then
-    on_info(
-      nil,
-      {
-        contents = {
-          kind = 'markdown',
-          content = { 'No extra information availaible!' },
-        },
-      }
-    )
+    on_info(nil, {
+      contents = {
+        kind = 'markdown',
+        content = { 'No extra information availaible!' },
+      },
+    })
   end
 
   used_client.request('textDocument/hover', params, on_info, bufnr)
diff --git a/lua/symbols-outline/utils/init.lua b/lua/symbols-outline/utils/init.lua
index 29465dd..1b00738 100644
--- a/lua/symbols-outline/utils/init.lua
+++ b/lua/symbols-outline/utils/init.lua
@@ -38,4 +38,76 @@ function M.debounce(f, delay)
   end
 end
 
+function M.items_dfs(callback, children)
+  for _, val in ipairs(children) do
+    callback(val)
+
+    if val.children then
+      M.items_dfs(callback, val.children)
+    end
+  end
+end
+
+---Merges a symbol tree recursively, only replacing nodes
+---which have changed. This will maintain the folding
+---status of any unchanged nodes.
+---@param new_node table New node
+---@param old_node table Old node
+---@param index? number Index of old_item in parent
+---@param parent? table Parent of old_item
+M.merge_items_rec = function(new_node, old_node, index, parent)
+  local failed = false
+
+  if not new_node or not old_node then
+    failed = true
+  else
+    for key, _ in pairs(new_node) do
+      if
+        vim.tbl_contains({
+          'parent',
+          'children',
+          'folded',
+          'hovered',
+          'line_in_outline',
+          'hierarchy',
+        }, key)
+      then
+        goto continue
+      end
+
+      if key == 'name' then
+        -- in the case of a rename, just rename the existing node
+        old_node['name'] = new_node['name']
+      else
+        if not vim.deep_equal(new_node[key], old_node[key]) then
+          failed = true
+          break
+        end
+      end
+
+      ::continue::
+    end
+  end
+
+  if failed then
+    if parent and index then
+      parent[index] = new_node
+    end
+  else
+    local next_new_item = new_node.children or {}
+
+    -- in case new children are created on a node which
+    -- previously had no children
+    if #next_new_item > 0 and not old_node.children then
+      old_node.children = {}
+    end
+
+    local next_old_item = old_node.children or {}
+
+    for i = 1, math.max(#next_new_item, #next_old_item) do
+      M.merge_items_rec(next_new_item[i], next_old_item[i], i, next_old_item)
+    end
+  end
+end
+
 return M
diff --git a/lua/symbols-outline/writer.lua b/lua/symbols-outline/writer.lua
index 1849a89..e119940 100644
--- a/lua/symbols-outline/writer.lua
+++ b/lua/symbols-outline/writer.lua
@@ -1,5 +1,6 @@
 local parser = require 'symbols-outline.parser'
 local config = require 'symbols-outline.config'
+local ui = require 'symbols-outline.ui'
 
 local M = {}
 
@@ -21,7 +22,7 @@ function M.write_outline(bufnr, lines)
   vim.api.nvim_buf_set_option(bufnr, 'modifiable', false)
 end
 
-function M.add_highlights(bufnr, hl_info)
+function M.add_highlights(bufnr, hl_info, nodes)
   for _, line_hl in ipairs(hl_info) do
     local line, hl_start, hl_end, hl_type = unpack(line_hl)
     vim.api.nvim_buf_add_highlight(
@@ -33,6 +34,8 @@ function M.add_highlights(bufnr, hl_info)
       hl_end
     )
   end
+
+  M.add_hover_highlights(bufnr, nodes)
 end
 
 local ns = vim.api.nvim_create_namespace 'symbols-outline-virt-text'
@@ -58,6 +61,30 @@ local function clear_virt_text(bufnr)
   vim.api.nvim_buf_clear_namespace(bufnr, -1, 0, -1)
 end
 
+M.add_hover_highlights = function(bufnr, nodes)
+  if not config.options.highlight_hovered_item then
+    return
+  end
+
+  -- clear old highlight
+  ui.clear_hover_highlight(bufnr)
+  for _, node in ipairs(nodes) do
+    if not node.hovered then
+      goto continue
+    end
+
+    local marker_fac = (config.options.fold_markers and 1) or 0
+    if node.prefix_length then
+      ui.add_hover_highlight(
+        bufnr,
+        node.line_in_outline - 1,
+        node.prefix_length
+      )
+    end
+    ::continue::
+  end
+end
+
 -- runs the whole writing routine where the text is cleared, new data is parsed
 -- and then written
 function M.parse_and_write(bufnr, flattened_outline_items)
@@ -66,7 +93,7 @@ function M.parse_and_write(bufnr, flattened_outline_items)
 
   clear_virt_text(bufnr)
   local details = parser.get_details(flattened_outline_items)
-  M.add_highlights(bufnr, hl_info)
+  M.add_highlights(bufnr, hl_info, flattened_outline_items)
   M.write_details(bufnr, details)
 end