As others have said, a license is a legal tool that allows you to enforce how you want your program to be used.
And in the case of FOSS this is a really big issue, because just publishing code doesn’t put it into the public domain, and leaves you open to exploitation by big companies.
There are various types of licenses, but for FOSS the main ones are unlicensing and Copyleft licenses.
Unlicensing essentially declares your code public domain, so anybody can use it for any purpose.
Copyleft licenses are usually fairly permissive, especially for individuals, but obligate that any offshot/fork must also be made Copyleft - so prohibits close sourcing of your work.
As others have said, a license is a legal tool that allows you to enforce how you want your program to be used.
And in the case of FOSS this is a really big issue, because just publishing code doesn’t put it into the public domain, and leaves you open to exploitation by big companies.
There are various types of licenses, but for FOSS the main ones are unlicensing and Copyleft licenses. Unlicensing essentially declares your code public domain, so anybody can use it for any purpose. Copyleft licenses are usually fairly permissive, especially for individuals, but obligate that any offshot/fork must also be made Copyleft - so prohibits close sourcing of your work.