Action history is access through the special button on the ribbon, toolbar and item context menu.

Action history shows the execution history of all the actions in a specific column for a specific list item or document. Click on Action History in any view containing the action column or within the action column on Edit/Display form of the item to show the pop-up window listing all the actions performed on the item. The actions are grouped by name and show when each action was executed, by whom and with what outcome.

You can always disable logging for a specific action under Advanced Settings.