When I type I am consistently hitting a different key than one I intended to hit. Lots of times the spell checker identifies my error to me and lets me correct it. Other times my mistake produces an entirely different word than the word I wanted to use, but since it is a real word the spell checker does not help me identify the error.

Three of the most easily typing errors that produce the incorrect word are using the “W” in place of the “T” or vice versa.

What, When and Where can become That, Then and There with the substitution of one letter. Even though it is a small error, it can really change the meaning of what you are trying to say or at other times confuse the reader.

This brings me to my cardinal rule: proof read, set the item aside for a time, and then proof read it again. It helps you errors on the second reading that you missed the first time.