What is the meaning of "from within"?

Question

I need your help please.

What is the meaning of "from within" and when can use it?

For Example, I met the following sentence when I was reading an article :

A column segment is a column of data from within the rowgroup.

Answer 1

The phrase from within is opposite in meaning to from outside. In other words, it means inside:

A column segment is a column of data inside the rowgroup.

Another example:

No one can help you, but yourself. So, your personal development can only happen from within.