The Cathedral and the Bazaar by Eric S. Raymond in First Monday, March 1998.
Not required, but well worth your time.
If you want to read only part of it, read
Necessary Preconditions for the Bazaar Style and
The Social Context of Open-Source Software.
Not everyone agrees with Raymond, however.
You might take a glance at
A Second Look at The Cathedral and the Bazaar
by Nikolai Bezroukov in First Monday, December 1999.
Also not required, but if you are interested in the Open-Source issue, you might want to learn about all sides of the issue.