Is there a way to run Linux on a windows 10 computer without having to use a dual boot system? Is there a way to practice using some different distributions of Linux on a Windows 10 computer ?
Yes, you can run it as a virtual machine with a program like virtualbox. Switching between Linux distributions is easy then.
or you can use WSL, that'll let you run a full linux environment directly in windows. currently it'll let you run ubuntu, kali, suse, debian, or centos. you won't get the full linux desktop, but you can install Xming on windows and export the linux display, so you can start full graphical linux apps, gimp, firefox, gedit etc from the linux terminal and get the full application window, running under linux and displaying in the windows desktop.