Quickie content to be added, but here is already an http://www.owasp.org backgrounder:

The Open Web Application Security Project (OWASP) is dedicated to finding and fighting the causes of insecure software.

Our open source projects and local chapters produce free, unbiased, open-source documentation, tools, and standards.

The OWASP community also facilitates conferences, local chapters, articles, papers, and message forums.

The OWASP Foundation, a not-for-profit charitable organization, ensures the ongoing availability and support for our work.

Participation in OWASP is free and open to all, as are all the materials created.