How is a search warrant related to probable cause?

Because of the bill of rights we have the right to refuse a search or seizure unless the officer has probable cause (Definite evidence of a crime) If the crime is not urgent enough the officer may have a search warrant issued under probable cause and will then search you

Well, if an officer wants a warrant to check your house or car there has to be a GOOD reason! He can't just say something like "Hmmm… Their house is red, that seems sketchy! I'll get a warrant!" that is NOT probable cause! But, say someone is a wanted criminal, this is a GOOD reason to check their house, just in case there is evidence that can help them in the case against the criminal.  

I hope this helps!