Research is a systematic investigation to discover answers to questions through intellectual and methodical processes. There are three main types of research: applied research seeks practical solutions to problems, pure research advances knowledge for its own sake, and action/developmental research balances problem solving with analysis in a collaborative context. Historical, descriptive, experimental, and causal-comparative research are specific methodologies. Historical research tests past reports, descriptive research conveys "what is", experimental research controls variables to predict outcomes, and causal-comparative research investigates existing relationships without manipulation.