Image previews are typically very small, adding very little to the file size of the saved document.
If Photoshop crashes unexpectedly, the program automatically tries to recover and open your file. You can also set options to automatically save the file based on a time interval or save the file in the background, which allows you to keep working while Photoshop saves behind the scenes a progress information appears in the Document tab and Status bar. The File Handling preferences provide several options that modify what information is saved with a file. Photoshop lets you save files using different formats, including TIFF, EPS, JPEG, or BMP. Sooner or later, you’ll have to save the file (document) you’ve created in Photoshop. Learn More Buy Setting File Handling Preferences