diff --git a/.tmux.conf b/.tmux.conf
index 395b65f..4b74863 100644
--- a/.tmux.conf
+++ b/.tmux.conf
@@ -4,12 +4,22 @@
 bind-key C-t send-prefix
 unbind-key C-b
 
+# --- key bindings ---
+# emacs keybindings
+set -g mode-keys emacs
+
+# history size
+set-option -g history-limit 100000
+
 # --- status bar ---
 # normal
 set -g status-fg white
 set -g status-bg green
 set -g status-attr bold 
 
+# window settings
+set-option -g renumber-windows on
+
 # status line left side
 
 # status line right side
@@ -27,8 +37,47 @@
 set -g pane-active-border-bg default
 set -g pane-active-border-fg green
 
-# window settings
-set-option -g renumber-windows on
+# --- switch a pane ---
+# Prefix + C-p : select a upper pane
+# Prefix + C-n : select a bottom pane
+# Prefix + C-b : select a left pane
+# Prefix + C-f : select a right pane
+# Up
+bind -r C-p select-pane -U
+# Down
+bind -r C-n select-pane -D
+# Left
+bind -r C-b select-pane -L
+# Right
+bind -r C-f select-pane -R
 
+# --- resize pane ---
+# -r means command repeatable,
+#
+# ex) Prefix + +++ means resize a pane of top +3.
+#
+# Prefix + + : resize a pane of top
+# Prefix + - : resize a pane of bottom
+# Prefix + < : resize a pane of left
+# Prefix + > : resize a pane of right
+# Up
+bind -r + resize-pane -U 1
+# Down
+bind -r - resize-pane -D 1
+# Left
+bind -r < resize-pane -L 1
+# Right
+bind -r > resize-pane -R 1
+
+# --- others ---
+# reload config file.
+bind R source-file ~/.tmux.conf \; display-message "source-file done"
+
+# --- plugins ---
 # install tmux plugin to save and restore sessions.
+# prefix + Ctrl-s : Save
+# prefix + Ctrl-r : Restore
 run-shell ~/tmux-resurrect/resurrect.tmux
+
+# auto saving current windows every 60 seconds.
+set -g @continuum-save-interval '60'