The Linux Test Project (usually referred to as LTP) is a body of regression tests designed to confirm the behavior of a build of the Linux kernel. According to the LTP web site the project was started by SGI and is now maintained by IBM. Source code is available at http://ltp.cvs.sourceforge.net/ltp/ltp/.
In Simple English terms, The Linux Test Project is a group aimed at testing and improving Linux. The goal of the LTP is to deliver a suite of automated testing tools for Linux as well as publishing the results of tests they run.