Open Source SW License is a contract specifying how to use
and the range of terms between an Open Source SW developer and a user.
Therefore, you should observe license defined by a developer to use Open Source
SW; if not, license violation and copyright infringement occur, followed by
punishment. This Open Source SW License basically guarantees free use,
revision, and distribution by users.
Open Source SW makes and operates such license to make it compulsory to open source code
within the legal limit for SW developed using Open Source SW.
As of June 2012,
there are 69 licenses according to OSI that is in charge of Open Source SW
licensing. However, there are a limited number of licenses being frequently
used in practice.