As you may know, the History palette in Photoshop allows you to keep track of all the commands, brush strokes and changes you make when you’re working on an image. The problem is, it only allows a certain number of history “states” to be recorded and even then they are temporary, i.e. when you close the file, the history disappears. BUT, there is a way around this and it’s called the History Log.
The history log in Photoshop lets you keep a running record of every step or change you make to your image and save it in a text file to look at later. This is very helpful if, for example, you’re writing tutorials or if you’re doing a lot of experimentation in Photoshop. You can play and Photoshop will keep track of what you’re doing.
To turn on this History Log, choose Edit > Preferences (PC) or Photoshop > Preferences (Mac), and choose General. Turn on the checkbox for History Log, and then you can decide if you want the log items embedded into the file (metadata), written to a text file, or both. Pretty handy.