It can be usefull to create automate actions if we have to do the same operation on several files. This could take a lot of time but with Actions we can record our actions and apply them to the files we need to modify.We open the first file, we go on
Window –> Actions to open that panel on the side of screen.
Create new action and rename it, then click on record. From this moment all your actions will be recorded untill you play stop button.
Now make all the changes to the file. In this case, we change image size and then export jpg for web.
We save the file then we stop the record.
Now we click File –> Automate –> Batch…
Select the action, the source folder where the files are, press ok.
Select the destination folder, press ok
All your files will now be processed and saved in the destination folder.
You can also turn off single activities of the action to skip a step.