It turns out that when light travels through the mostly emptiness of space, it can travel amazingly far without being significantly diminished. So we see galaxies the same way we see stars - you can see some with the naked eye, in fact, but to see detail you need a telescope. They come in somewhat different configurations, but generally look like this:

image

We don’t know exactly how many there are, we have to estimate it, and the range of estimates is huge: between 100 billion and 200 billion!

How do we estimate it? By counting the galaxies in a teeny tiny area of the sky, and then multiplying by that fraction. There are an amazing number of galaxies that are viewable in an area of the sky the size of the head of a pin held at arm’s length. It looks like this;

image

By the way, the galaxy at the top of this comment is eighty million light years away. That means the light were seeing from it now left eighty million years ago; we’re seeing back in time.