Lots of answers saying that it the delete key. That not correct. A proper backspace italic does not delete the character; it just moves the cursor. On a Mac it the leftmost of the set of keys with arrows in the lower right corner of the keyboard. Consider You notice you left out a letter when you spelled bacspace and you want to go back to add the k. If you use the delete key to get there youll have to re all the following letters; if you use backspace you can just add it in.