There is a various groups sort and publish approved lists of FOSS “Free and Open Source Software” licenses. The Open Source Initiative (OSI) is one such organization keeping a list of open-source licenses. The Free Software Foundation (FSF) maintains a list of what it considers free.
FSF's free software and OSI's open-source licenses together are called FOSS licenses. "Free software" and "open source software" are two terms for the same thing: software released under licenses that guarantee a certain, specific set of freedoms.
The FSF's Free Software definition focuses on the user's unrestricted rights to use a program, to study and modify it, to copy it, and redistribute it for any purpose, which are considered by the FSF the four essential freedoms.
The OSI's open-source criteria focuses on the availability of the source code and the advantages of an unrestricted and community driven development model.
This is a list of Licenses that are popular, widely, or with strong communities as listed by OSI: Apache License, 2.0 (Apache-2.0) BSD 3-Clause "New" or "Revised" license (BSD-3-Clause) BSD 2-Clause "Simplified" or "FreeBSD" license (BSD-2-Clause) GNU General Public License 3.0 (GPL) GNU General Public License 2.0 (GPL) GNU Library or "Lesser" General Public License (LGPL) MIT license (MIT) Mozilla Public License 2.0 (MPL-2.0) Common Development and Distribution License (CDDL-1.0) Eclipse Public License (EPL-1.0)