diff --git a/lua/keymaps.lua b/lua/keymaps.lua
index 6dc84c0..5f6d7ee 100644
--- a/lua/keymaps.lua
+++ b/lua/keymaps.lua
@@ -40,6 +40,16 @@ map("n", "<C-h>", "<cmd>Pick help<cr>", { desc = "Find: help tags" })
 map("n", "<C-e>", "<cmd>Oil<cr>", { desc = "File explorer (Oil)" })
 map("n", "<C-k>", "<cmd>Pick keymaps<cr>", { desc = "Find: keymaps" })
 
+-- Folding (stock Vim fold keys, remapped to themselves just so they show up
+-- with descriptions in the keymap picker <C-k>)
+map("n", "za", "za", { desc = "Fold: toggle under cursor" })
+map("n", "zc", "zc", { desc = "Fold: close under cursor" })
+map("n", "zo", "zo", { desc = "Fold: open under cursor" })
+map("n", "zR", "zR", { desc = "Fold: open all" })
+map("n", "zM", "zM", { desc = "Fold: close all" })
+map("n", "zj", "zj", { desc = "Fold: move to next fold start" })
+map("n", "zk", "zk", { desc = "Fold: move to previous fold end" })
+
 -- Spell
 map("n", "<leader>sc", function()
     vim.wo.spell = not vim.wo.spell
diff --git a/lua/options.lua b/lua/options.lua
index 5efe8a3..1d1357d 100644
--- a/lua/options.lua
+++ b/lua/options.lua
@@ -12,6 +12,14 @@ o.winborder = "single"
 o.termguicolors = true
 o.autoread = true
 
+-- Folding: native treesitter folds (function/class/block-aware), no plugin needed.
+-- `foldmethod=diff` (used automatically in :diffthis / fugitive / diffview windows)
+-- takes over on its own and isn't affected by this.
+o.foldmethod = "expr"
+o.foldexpr = "v:lua.vim.treesitter.foldexpr()"
+o.foldlevel = 99 -- start with everything open
+o.foldlevelstart = 99
+
 vim.api.nvim_create_autocmd({ "FocusGained", "BufEnter", "CursorHold", "CursorHoldI" }, {
     command = "if mode() != 'c' | checktime | endif",
 })