Complex sentence: Scientific Linux (SL) is a free operating system, co-developed by Fermi National Accelerator Laboratory and the European Organization for Nuclear Research (CERN), and which aims to be 100% compatible with and based on Red Hat Enterprise Linux.
Split into simpler sentences: Scientific Linux (SL) is a Linux distribution produced by Fermi National Accelerator Laboratory and the European Organization for Nuclear Research (CERN). It is a free and open source operating system based on Red Hat Enterprise Linux and aims to be 100% compatible with and based on Red Hat Enterprise Linux.