Free disk space to install software

Hi everybody,
I'd like to ask you about the "Free Disk Space" that we only have to install software in Linux.
In windows, you are not restricted to a limited space, which you must select before installing the system, and you can install your software anywhere on any drive that has free space.
but here in Linux, i think that you have to shrink and put aside a fixed amount of space before doing anything and use only that to install any new software.
Now It seems that i'm running out of space in my Linux and in the near future, i won't have any free space to install anything at all.
How can i overcome this problem?
Thanks
I'd like to ask you about the "Free Disk Space" that we only have to install software in Linux.
In windows, you are not restricted to a limited space, which you must select before installing the system, and you can install your software anywhere on any drive that has free space.
but here in Linux, i think that you have to shrink and put aside a fixed amount of space before doing anything and use only that to install any new software.
Now It seems that i'm running out of space in my Linux and in the near future, i won't have any free space to install anything at all.
How can i overcome this problem?
Thanks