Definition:
Exact match is a setting within Google AdWords that means only users who use the same word, phrase, or a close variation (such as a misspelling or plural) will be served your PPC ad.
Resources:
Conversion marketing – Glossary of Conversion Marketing.
Over 300 tools reviewed – Digital Marketing Toolbox.
A/B testing software – Which A/B testing tool should you choose?
Keyword research – How to do keyword research?