Most browsers have an easily accessible history option where you can browse through and choose previously visited sites to open again. Not only are histories available, but some browsers including Safari have options for reopening the last closed window or even all the windows from the last session when the browser was run. In Safari these are available in the "History" menu.
Open the last closed window
This feature in Safari is exceptionally useful if you inadvertently close a window containing a page or pages you needed to view. Granted you can always go to the history list … Read more