Clauses

Clauses are building blocks of sentences. It always include a VERB.

There are two types of clauses: main and subordinate clauses.

Main Clause

A main clause is a group of words which is, or could be, a sentence on its own.

Subordinate Clause

A subordinate clause is a clause which could not form a complete sentence on its own.

Conjunctions/connectors (because, although, after, if, ...) and relative pronouns (who, whom, whose, which and that) do not introduce main clauses. So you can be pretty sure that it is a subordinate clause.

She was eating a bowl of 'laksa'.

[main clause]

 

He danced in the street	because he was feeling happy.
[main clause]	[subordinate clause]

 

There is a good explanation from Oxford Dictionaries which you may refer to for more examples here.