Software is considered as a work of art in the eyes of the law, similar to a painting, a poem, or a movie script. As such, even if you share your art with the rest of the world to see, it does not mean that anyone can download it and use it as they please. Instead, they have a legal obligation to receive approval from the author who has copyrights on the software.
An open source license is a legal and binding contract between the author and the user, declaring that the software can be used in commercial applications in certain conditions. The license is what turns software components into open source components and allows developers to use that software — as long as they keep to the specific terms and conditions as laid out in the license.
Each open source license states what users are permitted to do with the software components, their obligations when using them, and what they cannot do as per the terms and conditions. This might sound simple, but there are over 200 open source licenses out there, varying in complexity and requirements. It’s up to each developer or organization to choose which components are most compatible with their policies and existing software to ensure that they remain compliant.