What do you mean by indentation of a paragraph?

First let us discuss in general what indention means. When one is writing text on to a computer or onto a piece of paper, one normally starts on the left hand side of the page and writes each line so that it begins set in the same amount from the edge of the page. This gap is called a 'margin'.

A paragraph indentation will start a new paragraph with the margin for that paragraph shifted to the right of the line of the page margin. The indentation can be applied to all the lines of that paragraph (as I have done in this example) or just the first line.

The above is an example of indentation of a paragraph.