I always have many tabs open the same time in my browsers during the time I am on my computer. The last thing I want is to lose them because of the browser being closed either accidently or due to the computer reboot. And that’s why I always set in all browsers so that whatever happened to cause them shut down they always open the tabs from last session automatically for me when reopened. And here is how to set them.
Go to Chrome Option page by clicking on the wrench icon and choosing Options. In Basics tab, choose option "Reopen the pages that were open last" on Startup section.
Click the orange Firefox tab at the top left corner, and choose Option. In General tab, select "Show my windows and tabs from last time" from the When Firefox starts dropdown list. Click OK to save the change.
Click the Gear icon on the top right corner, and choose Preference. In General tab, select "All windows from last session" from the Safari opens with dropdown list.
Well, not so obvious that you can have the similar option to set so that it opens all tabs from last sessions every time when it starts. But here is a way of doing so.
In IE 9, there is a tab preview page when you have new tabs open. From there, you can find a link that says "Reopen last session". Clicking on it will open all tabs from last session for you. It’s not automatic but at least there is a way you can have all your lost tabs back. If you wish, you can always set the tab preview as your home page in IE so that you can reopen tabs right from there.