What is SOFTWARE LICENCE?, Why is it important?

Question

what is software licence agreement and why is it important

licence like : FOSS, APACHE, EULA?
what is that?

open source vs license.
what is the essential difference from the developer point of view?

what is need for commercial deployment?

Please feel free to answer and please tell me what is your opinion? help...

Answer 1

You can read up on open-source licenses, and why we need them. This link also addresses a few common questions that people have on the topic:

https://opensource.org/licenses

Answer 2

Thanks, and what with commercial licence