There was a time when people had to check spelling by looking at a physical paper dictionary. The ultra-careful might even look at special dictionaries written especially for pointing out common spelling mistakes. In the second half of the 20th century computer spell checkers appeared to point out possible errors. As computer became more powerful and software developers kept adding features and functions like providing likely correctly spelled words. We are now at a point where even phones goes beyond spell checking and provides predictive text that attempts to determine what word you are typing before you finish typing. This of course leads to all kind of potentially humorous text messages by people who did not check what they typed before pressing send.
NPR has a great interview (audio + text) with Jillian Madison, the founder of the Damn You Auto Correct! site, and linguist Ben Zimmer.
They discuss some of the funny text messages people have submitted to the site and the new book that publishes the best predictive text errors from the site: “Damn You Autocorrect!”.
As yes, the name of the site and the title of the book spells “autocorrect” differently. The site name has a space between “auto” and “correct” while the book does not.