Open source software is the general name for the different categories of software provided to users under an open source license that allows access to the source code as a minimum. Well-known examples are the Linux operating system, the Firefox browser and the Apache servers.
Is free software in the public domain? Is it free of rights?
The protection of software by copyright allows the rightsholders to determine the conditions under which they will market it, such as the price and the limits to the use of the software.
These authorizations granted to users, as well as the limits and conditions, are set out in a license.
The licenses that accompany software are generally very restrictive. For example, the license prohibits the creation and distribution of copies of the software and the modification of the software, limits its use to private purposes only, and prohibits the installation of the software on more than one workstation, etc.
Free software is also protected by copyright. But the accompanying license grants users much more rights. However, these licenses are subject to a number of conditions. You cannot do whatever you want with open source software.
Rights and conditions of open source licenses for software users
The licenses that apply to open source software are different from traditional licenses, as they confer a number of rights for using the software: the right to use the software as widely as possible, the right to make copies, give or sell copies, the right to modify the software, etc.
However, keep in mind that there are often conditions that accompany these rights - for example, the obligation to mention the names of the authors on distributed copies, the obligation to provide a copy of the source code, etc.
There are a number of free licenses, each with different rights and conditions. It is, therefore, important to read the license carefully.
Rights and conditions of open source licenses for software developers
Unlike the majority of traditional computer programs, open source software can be used as a basis for developing other programs. Indeed, you can modify a piece of free software and then distribute the new program you created. There are even libraries available on the Internet with function codes under open source licenses. A software developer can take functions from this library into his program or link to them without having to rewrite those pieces of programming code.
Please note that there are numerous types of open source software licenses in circulation, and some licenses attach conditions to the freedoms guaranteed (granting access to the source code, listing the authors, listing the changes, etc.). A very strict condition is the so-called "copyleft" clause, which is included, for example, in the GNU-GPL (General Public Licence). That condition states that a computer program, which includes software elements covered by a GPL, must itself be distributed under a GPL. Thus, a commercialization of the program resulting from that integration must be under a free license.
Here too, in view of the variety of free licenses, it is important to read the license carefully to find out which rights and obligations it contains.