Most people confuse the words then and than. Here is the answer:

Than is a conjunction used with comparisons. 

1. For example: Laika is smaller than Sam.
2. For example: When I looked at my money, I had less than I thought I had.

Then is an adverb or an adjective that refers to the time in the past or the future.

1. For example: They say machines will do all the work in the future, but I think I'll be retired by then. 
2. For example: The whole family had a leisurely breakfast. We then went outside to enjoy the beautiful weather.

In case you weren't sure.