A think tank is "an organization, institute, corporation, or group that conducts research and engages in advocacy in public policy." (Sourcewatch.org).
Most are non-profit, but some are funded by governments, advocacy groups, or corporations, and may derive revenue from consulting or research work related to their projects. They can be non-partisan or partisan, so pay attention to the goals of the organization when using the information they generate.
When using information from a think tank:
There are many different methods that you can use to determine whether a source is credible. One great method you can use is called lateral reading. Lateral reading is a skill used by professional fact-checkers that helps them quickly review a source and determine whether that source is credible or not. This means instead of only staying on one webpage to determine if a source is credible, lateral reading encourages you to leave the webpage and use other webpages to decide if a source is credible or not.
When you only stay on one webpage, you can only see what that source is saying about themselves. A source might be presenting themselves in a way that is not entirely accurate. Reading vertically (only staying on one webpage) is very time-consuming and does not give you a full indication of the credibility of the source.
Instead, open multiple tabs in your browser to follow links found within the source and do supplemental searches on names, organizations or topics you find. These additional perspectives will help you to evaluate the original article and can end up saving you time.