Face validity is the extent to which something looks as if it will measure what it is supposed to measure (e.g. Relevant questions on a questionnaire.)
Construct validity is the extent to which a test measures all aspects of behaviour.
Concurrent validity is the extent to which a test correlates well with a measure of the same thing that has previously been researched.
Predicative validity refers to the extent that a measure can predictfuture behaviour.
The splithalf method is used to measure internal reliability (particularly in self reports) where repeat questions are asked to check how consistent the participants responses are.
The test-retest method is used to measure the external reliability of research. It is where participants are tested more than once to check they are getting consistent results.