How do I turn this text thing off?

Like sometimes when Im typing in windows, I make a mistake and when I type in that mistake (trying to fix it), it deletes the letters ahead of that mistake.

If you hit the "Insert" key, it will overwrite the characters in front of the cursor rather than inserting characters in the middle of your sentence.

I do it all the time. 'tis a pain in the posterior.

Just be careful not to hit that 'Insert' key.

I argue (poorly) that the insert key is thoroughly useless.

Then I'll argue(expertly) that the insert key is useless?

Can anyone give an example of why it is needed today?

Sometimes when typing, going into insert mode is a good thing. If I spell a word with one letter mistyped, I can hit insert and type the next letter and viola, it overwrites the mistake. Faster than positioning the cursor, hitting backspace or delete, then typing the new letter.

Also, CTRL+Insert = copy, Shift+Insert = paste. That sometimes works in places that CTRL+C and CTRL+V don't. It's also easy to hit those keys with your right hand. Depending on how you type, it can be faster to use your right hand for copy/pasting sometimes than using your left. Often I'll hold Shift with my left hand, use the arrow keys/page(up|down)/home/end with my right to highlight things, and copy/paste with my right since my hand's already right there.

EDIT: Added more reasons.

Bah, I forgot to put the disclaimer at the end of my question:

Can anyone give an example of why it is needed today except for Unne because he'll find good reasons? :p

That block of 6 keys there is handy for secondary functions in 3D games, as well as for changing settings on the fly in emulators :p

Unne's responses are pretty user-specific. I use ctrl-c/v expertly, and I have no problem fixing my typos by retyping words over and over and over and over instead of taking the time to use the insert function.

I also don't typically use scroll lock (what does it even do?) either. Whenever I see a flowing mess of code/output, I hit the pause button. There's a 'SysRq' under my Prt Scr key. I don't know what that does either. There's a weird button to the left of my right ctrl button that seems to do what right clicking does. I don't use that either. I also don't use the right windows key...

Ah forget it. If I had my way the keyboard would only have 95 keys and would look too odd.