Free software means software that respects the user's freedom.
There are four essential freedoms that the user of software should always have:
Freedom 0: Freedom 0 is the freedom to run the program however you wish.
Freedom 1: Freedom 1 is the freedom to study the source code of the program and change it to make the program do as you wish.
Freedom 2: Freedom 2 is the freedom to distribute copies of the program to others when you wish. This includes republication of the program.
Freedom 3: Freedom 3 is the freedom to distribute copies of your modified versions to others when you wish. This includes republication.
If you have all four of these essential freedoms, then the program is free software, which means that the social system of the distribution of the program is an ethical system that respects the freedom and community of the users.
If one of these freedoms is missing, then the program is proprietary software, meaning that it keeps the users divided and helpless, and gives the developer power over the users.
This is an injustice.

Proprietary software should not exist and should not be used.
If you want to have freedom, the only way you can have it while using computers is by rejecting proprietary software