You know, by commenting like this you're inviting me to chime in. Which means I might not shut up. ;) Most spell checkers take the word you typed and generate

You know, by commenting like this you're inviting me to chime in. Which means I might not shut up. ;) Most spell checkers take the word you typed and generate some number of suggestions. Typically this is done by finding every word you can get from the misspelled word by making one or two changes. These changes are usually deleting letters, inserting letters, transposing letters, and changing letters. What can we get from "helo"? help (o to p), hello (insert l), hell (delete o), etc. Which one is the best one to choose? You're claiming that "helo" should always be hello. Most spell checkers have some heuristic they use to rack and stack words. They may take into account which types of mistakes people make most often. This type of spell checker may say that a missing letter is a more likely error than accidentally changing an o to a p. Actually this is a bad example because o and p are next to each other on the keyboard. So some spell checkers would probably rate this error as very likely. After the Deadline doesn't work like that. It looks at edit distance (how many changes were required) and it looks at how well the suggestion fits the context of the misspelled word. If you type: "helo" by itself. AtD suggests help. Fine. How is AtD supposed to know you want hello when there are so many other good candidates? So what does AtD do? It looks at context. Try these examples with AtD: I need helo. Make sure you say helo. I helo my darling. Now try these in your favorite writing software. Any one is fine with me. Go to MS Office, Firefox, Chrome, GMail, Apple text editor. You'll see the difference.