The words then and than look similar, but their uses are very different.

Then
The word then usually relates to time. It is most commonly used as an adverb. It has the following meanings:

Go to the traffic lights, then turn right.
It went dark, then there was a scream.
The council members argued for three days then eventually came to a decision.

Than
The word than introduces a comparison. It is most often seen with comparatives and words like more, less and fewer.
Craig is smarter than Paul.
Money is better than poverty, if only for financial reasons.
Russia is even more spacious than Canada.

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