Is an indentation (Tab button in Word) needed for a new paragraph when you start one? I was told to do that a long time ago but 3 years after I stopped doing it and have done it since.
Are you meant to indent when you start a new paragraph?
I'm not an expert here but I thought I would illustrate two different styles of paragraphs:
The first pair of paragraphs are not indented, there is line-space between them.
The second pair of paragraphs are delineated by indenting the first line. Typically one would use double line-spacing with indentation, I show them compacted to better illustrate the difference.
What's important isn't which is more appropriate than the other (though there certainly are situations where one would be required over the other). The important thing is that the reader is able to distinguish where one paragraph ends and the next begins.
If you were to use both line-spacing and indentation of paragraphs, that would simply be redundant.
What's important is that it's clear to your reader where paragraphs begin and end, and that the text is laid out in a way that's easy to read. Often if you're writing for a publisher, newspaper or magazine, there will be a house style that will dictate the layout. If you're writing for yourself you're free to choose what you prefer.
Indents were (and to some extent still are) much more common in printed material; this may be due to space restrictions and the cost of paper. Most articles I read on the internet - even very formal ones - use gaps to delimit paragraphs, and this does not strike me as "wrong" or "informal" in any way.