What causes the problem that "insert" tab solves?

Not having the insert tab on puts you in overstrike mode.

What is the name of the problem which is solved by using the “Insert” key.

And, what is the action that caused the problem? What must I have pressed by accident?

It’s not a problem. If you have the insert key on, you can insert text. If it is off, you are in overstrike mode. I don’t know how to say this any plainer than that.

@janbb we must not be referring to the same thing.

Guess not. What happens on your machine when the insert key is not on?

I’m not quite sure what you are talking about. Is it in a particular computer program? If so, which one? Or are you talking about a physical key on a keyboard?

@janbb Now I know, you might be referring to the “insert” key that happens to be with the numbers (on the right side), where you have to turn on and off, light goes on and off. I’m referring to the other one, the one among the 6 set of keys under the Print Screen key. So, nothing to turn on and off.

@PhiNotPi Yes it is the pysical key, I shouldn’t have put on (“software” as a tag)

It has happened a couple of times, suddenly for apparently no reason, while I’m typing the letter I just typed gets displaced by the letter I type next. Something like that.

That is “overstrike” as I have been telling you. And both insert keys do the same thing. It probably means you have inadvertently hit one of the insert keys by mistake.

Maybe you should pick up a copy of “Windows for Dummies.” I think it would help you.

I just tested them. When I use either of the “Insert” keys, whether the light is on or off, absolutely nothing happens.

http://en.wikipedia.org/wiki/Insert_key
www.computerhope.com/jargon/i/insertke.htm

On the keyboard I’m using now, the Insert key is next to my Delete key. If I press it, then as @janbb observes, you are able to type over text, instead of inserting new letters (pushing the existing letters in front further to the right) as you type. You won’t see anything happen… poof… when you hit it, but its effect should be clear if you go back and type over some text you’ve already written.

I have another Insert key in the number pad to the right of my keyboard. It shares a key with the number 0 on my number pad. If I switch off NumLock, then it functions exactly as the other Insert key does.

When you said “I know how to solve the problem by using the “Insert” tab” in your details, what problem were you referring to? Perhaps if you describe the problem that you solved, we’ll know which key you hit.

Computers used to be for data entry into small fields. Over strike mode was the default. That way, if you needed to edit a field, you just select the field and start typing, and the new data would over write the old data, without the added step of deleting the old data first. If you wanted to insert text into the middle of text that was already there (very rare in data entry), you had to manually put it into Insert mode. Hence, the insert key. Data entry systems would usually put you back in Overstrike mode as soon as you left the field you were working on.
Now that word processing is much more common than data entry, most computers default to Insert mode. But you can still activate Overstrike mode should you need by hitting the insert key.

Thank you all.
Anyway it happened once when I might have accidentaly touched the insert key. Since then I’ve been really careful not to hit any key by accident. But I as described above it ” suddenly for apparently no reason, while I’m typing the letter I just typed gets displaced by the letter I type next.”

So, the programers thought it is just too much work to just hit the backspace button to delete a text? That is the extra work? That is why this fuction got created? The first time it happened to me I had to find someone to show the problem to. It stopped me in my tracks, for hours and hours.