This feature is a little bit hidden
If you often restart your Mac, quit the Safari web browser to free up some RAM, or (gasp) Safari crashes, you’ll find the following tip quite useful.
Firefox has supported a feature that allows users to save an open session and reload it the next time they launch the browser. Safari did not support this out of the box in previous version, but with Safari 3 it now does.
However, unlike with Firefox where you get a pop-up message asking if you want to save and resume the session with the Safari web browser this feature is a bit hidden.
To test out this feature launch the Safari web browser and open some web pages in a few tabs. Then do a Cmd + Q to quit the browser. Now launch the browser again.
In the Safari menu click on History -> Reopen All Windows From Last Session. Your last browsing session should be back in its entirety, tabs and all. You now pick up your web browsing session exactly form where you left it.