Insert Key

The Insert Key on the keyboard allows you to have two options when you type.

When you have Insert turned on, when you type a word in the middle of a sentence, it pushes the sentence to the right and inserts the letters you are typing before the sentence.
When you have Insert turned off, when you type a word in the middle of a sentence, it replaces the letters that are in that location and doesn't push the sentence to the right.

Example.

There is the following sentence displayed on the screen

"When Jack went up the hill"

After typing "When Jack went up the hill" you realized you forgot to add "and Jill" and you try to insert "and Jill" in the sentence. Here is what happens when insert is off and on.

Insert is turned on - you put the curser after Jack and start typing. It will push "went up the hill" to the right and add "and Jill" to the sentence. Now it will read "When Jack and Jill went up the hill"

Insert is turned off - you put the curser after Jack and start typing. It will replace 8 spaces with "and Jill" and not move them to the right. Now it will read "When Jack and Jillthehill".

The insert key is located next to the Page Up, Page Down, Home, End, and Delete keys.