#INSERTKEY (INS) - Did you forget Me ?

The Insert key (often abbreviated INS) is a key commonly found on computer keyboard.

Previously, this button is the most irritated button when you press it then the normal cursor turns into a block cursor and also its function is a bit different from the normal cursor. Sounds sensible, right? Well it was until people started pressing it by accident and staring incredulously at the ruinous effect it had on their Word documents. It was annoying. In fact, it was so annoying that in 2007 Microsoft disabled it by default in Microsoft Word.Essentially, it only has a couple of functions, neither of which are all that important in the grand scheme of things, but if you are a die-hard word processing enthusiast, you may want to know, so here’s what it can do. When the cursor inserts a character at its current position, forcing all characters past it one position furthers. 

For example, if the normal cursor  is placed in front of any text, as you type, text is inserted and nothing is overwritten. However, if you press the Insert key and the normal  changes to a block cursor, as you type the text is overwritten . Not all programs allow you to change the insert method with the insert key. If the cursor does not change when you press Insert, text input mode toggling it is not supported.

One more usage is that ctrl+insert: copy, shift+insert: paste. It was the default copy-related shortcuts in most DOS editors (since ctrl+key shortcuts are almost unusable in command line). Nowadays almost no one knows that but those shortcuts are still in effect in Windows and Linux. 

It is primarily used to switch between the two text-entering modes on a personal computer (PC) or word processor.

1. The first is overtype mode, in which the cursor, when typing, overwrites any text that is present in the current location.

2. The other is insert mode, where the cursor inserts a character at its current position, forcing all characters past it one position further.

You can enable or disable this functionality in MS Office as it is  disabled by default.. You can activate it in the options:

Office button => "Word Options" => "Advanced" tab => "Editing options" header => "Use the Insert key to control overtype mode"