Think tanks are formed in response to the need to analyze and organize information in a coherent and relevant way. The problem that they are solving is not a lack of information, it's the abundance of information. Think tanks seek to sift through the wealth of information available to determine what is relevant and use that determination to shape public policy.
Think tanks can be classified in two ways: by their strategies and by their sources of funding.
The combination of these characteristics results in seven types of think tanks:
autonomous and independent
quasi-independent
university-affiliated
political party affiliated
government-affiliated
quasi-governmental
for-profit