Have you ever finished a complex sequence of steps in Photoshop, and later wished you could remember what those steps were? Photoshop offers an alternative to jotting all this down on a sticky note, legal pad or napkin. Photoshop can actually record these notes for you, keeping a detailed account (called a History Log) of each and every command that you perform. Here's how to set it up:
In Photoshop CS or later, choose Preferences > General. Select the History Log option. Then, you can save the Log Items either to Metadata or a Text File. If you choose Metadata, the log becomes part of the file you are editing, and can be viewed at any time by choosing File > File Info in Photoshop and choosing the History category on the left. If you choose Text File, you will be asked for a name and a location in which Photoshop will save a text file containing the log. You also can choose the level of detail you want Photoshop to record, from Sessions Only (the most basic) to Detailed.
Once selected, the preference setting will remain on and in effect, logging every change you make to every file you open, until you return to Preferences and turn it off. You may want to set up an Action to make it easy to turn the History Log preference on and off with a single click.