Tab Scissors and Tab Glue.
But Kendra, that is 2 extensions.
You caught me! It is 2 extensions; but they go hand-in-hand.
Tab Scissors lets you separate 2 tabs within one Google Chrome browser window. Tab Scissors splits the tabs into 2 smaller, equal sized windows allowing you to compare information side-by-side. The extension separates your window at the active tab and the one to its immediate left. If you have additional tabs open, the ones on the left stay in the left window and the ones on the right stay in the right window.
Tab Glue allows you to quickly put all of your tabs back together, into one large window. Your tabs remain in their original order. Tab Glue simply works in the reverse of Tab Scissors.