How many partition in Linux?

Answer 1

Linux can have as many partitions as you like, as it uses a unified filesystem structure. Usually you'll see 3-4:

The / partition, where it all comes together and you'll most likely find most your configuration, software, libraries, assets, documentation, etc.

The swap partition, which is where the Linux kernel can dump pages of memory when memory is running low or certain processes have been blocked for a long time.

The /home partition, where user data is stored, includes preferences, documents, media files, and misc user-specific data are kept. Often kept in its own partition to allow you to share the same user data across multiple operating systems, and also to allow you to reinstall Linux without having to waste a second on needless backups, as that partition need not be removed.

/boot partition, where the kernel, initramfs images, and bootloader files and configuration are kept. Often placed on its own partition for similar reasons as /home, to allow reinstallation of Linux without necessarily having to clear out boot data. IT also allows one to install multiple Linux instances and only having to define kernel parameters and initramfs locations for all of them from a single location. Also allows the system to keep booting if you were to remove Linux itself and go back to Windows without having to reinstall Windows.

You can put many other toplevel directories in other partitions, but not all of them. /usr, /tmp, /opt, and /var can be put on other partitions, as the system doesn't actually rely on them to come online, though they will all be needed for the system to become usable to the average user.

All the other toplevels need to stay on /, as the system absolutely needs them to function from the very moment early userspace finishes, not to mention single-user ("Maintenence") mode counts on everything an administrator would need being present at all times, which can't be guaranteed with separate partitions.