Have as many or as few partitions as you like. Many suggest keeping
/boot separate, mainly because some BIOS have trouble booting if the boot files are too far away from the start of the disk. You can have a
swap partition, but a file works just as well.
In the recommended case, you will create three partitions:
- One likely formatted Ext2 or FAT*, with mount point
- One likely formatted Ext4 or similar, with mount point
- A swap partition, which doesn't have a mount point
If you want to stray from this recommendation and use only a single partition, you want the one with mount point
/, the root of the filesystem. If you take this approach, then it is recommended that you create a swap file somewhere on this partition so that the system doesn't crash if you use all of your memory.
Any directory can be its own partition though. Some that are commonly split out are:
/boot for your kernel and
initrd — boot files
/home for all of your own files
/var for read-write files (in case you want to make
/ for the system itself — programs, libraries, configuration, etc.
/usr is sometimes separate from
/ but contains the same kinds of things
If you are using (U)EFI to boot instead of the old BIOS, you will likely not want a separate
/boot partition, but you will want to mount the system EFI partition as
/boot/efi. However, you should not reformat this partition, as it contains the boot files for any other operating systems installed as well.
Usually the installer will give you either a graphical utility to manage partitions, or a shell from which you can use
fdisk. You do want to be careful not to change your Windows partitions, though — and have a backup just in case, since you are modifying the drive layout.
On the system from which I am typing, I have
/boot of 200M
swap of 16G
/ of 40G
/var of 40G
/home of 835G
/var partition is much larger than necessary, and in fact would fit well within the free space of