Over the phone screening interview with a recruiter, followed by 1-on-1 phone technical interviews. Adequate performance will result in a second phone technical; outstanding performance will allow you to skip the second. Advancing beyond that results in an on-site review day with several interviews and chances to talk to Google employees. Nervousness is expected during every step, and mistakes will happen, but you needn't be discouraged by them. Google focuses on having a low false positive rate; not making it through doesn't mean you aren't an amazing person.

Implement a data structure X in your favorite programming language.

Implement an algorithm to solve X problem in your favorite programming language.