There are three types of compound words:
1) OPEN - space between the words such as a lot.
2) CLOSED - no space between words such as cowboy.
3) HYPHENATED - hyphen between words such as far-fetched.

Most people will make mistakes from time to time when it comes to many compound words. One of the most common is leaving out the space in "a lot." However, there are many examples which are confusing. For instance, why is it bedroom and bathroom, but living room has a space? Why is it everywhere without a space, but every time requires a space? For that matter, why is there a space in ice cream, but no space in snowball? No wonder so many people make mistakes when it comes to compound words!