The default install (no "custom partitioning") comes with a swap partition.
If you want to suspend-to-disk (hibernate), it is necessary. If you do not
want any swap partition (RAM should then always suffice), you can boot the
live media again, insert your USB key with the installed system and use
GParted (present on the live media) to remove the swap partition and extend
an adjacent partition, typically the one mounted on /home. The line in
/etc/fstab (that of the installed system) with "swap" in the third column
should then be removed.
If you want to keep the swap partition but have it disabled by default, you
must edit that same line of /etc/fstab (with root permissions) and turn the
fourth column, "sw", into "sw,noauto". Whenever you need the swap partition,
you fire 'sudo swapon' followed by the swap partition. For instance, if it is
/dev/sda5:
$ sudo swapon /dev/sda5
And, to turn the swap off:
$ sudo swapoff /dev/sda5
You can also read about swap files if do not want any swap partition but
still want to swap on occasion (the file is allocate with 'fallocate' and can
have any size you want).
