Imagine that you want to buy a gamer computer, so you go to an electronic store and after reviewing all your options, you choose one of medium quality. Then you go to your home to test your new computer. After playing some games you realize that for a certain game, you need more “power”, so in you open the CPU to inspect what can you do to improve it, and then you add more RAM memory, maybe you buy a better GPU, etc. In the end, you improved a product because you were able to do so and the parts of the computer was open to the user.
Now imagine that what you bought was a computer program and you were able to improve or customize the software. That is an open source software.
Open Source software is software that can be freely accessed, used, changed, and shared (in modified or unmodified form) by anyone
If you have an open source software, it means that you can view and freely modify the source code, something that you cannot do in other software that does not have this attribute. Something notable is that if you want to develop a program, by having it with open source you can get help form many people interested in you project, not only can help you with some bugs but also they can give ideas of how to implement something new or even provide you with possible code that can implement that thing. In a book called the Cathedral and the Bazaar ( you can check my post that talks about it ) it talks about experience and learning the author got when working with an open source software.
You don’t need to be a specialist in software to have its benefits, if you are a beginner you can learn by looking at the source code for example, or just check that the software is doing what is supposed to do.