Users of Chrome who have accidentally closed a tab can bring the tab back by holding down the Control and the Shift key and pressing T. Mac users use Command Shift T.
Control T
Control T will create a new tab.
Control Shift T
Control Shift T will bring back a tab you have closed. You can do this multiple times to bring back the last few tabs you closed. If you realize you need that website you were using 20 minutes ago you can look under your browser history or use Control Shift T to reload your tabs.
Control W
I am in the habit of using Control W to close a tab. Sometimes I accidentally use Control W when I do not mean to. Control Shift T allows me to quickly bring it back.