Ghost

A Ghost was the soul and spirit of a deceased person that could, under certain circumstances, appear as a visible manifestation to the living, and in even rarer circumstances, physically interact with the living world. However, following the destruction of the Other Side in The Vampire Diaries episode Home, it is unknown if ghosts can still linger on the Earth, or if their spirits move on to one of a number of afterlife dimensions.

Appearance
Ghosts do not appear any different dead than they did when they were alive. Whenever they appear to the living, they are usually seen dressed in the very same attire they were wearing at the time of their deaths. However, it's possible that ghosts can somehow change their appearance and manifest different clothing.

Powers and Abilities

 * Intangibility: Ghosts cannot physically feel nor can they be physically felt, unless they are given a physical foothold in the land of the living.
 * Vampire Abilities: If a vampire becomes a spirit, they will still possess their vampire powers. Vampire ghosts are capable of showing their fangs, with Kol Mikaelson being the first to do so.
 * Werewolf Abilities: If a werewolf becomes a ghost, they will still possess their werewolf powers.
 * Witch Abilities: If a witch becomes a ghost, they will still possess their magic as a ghost. It has been shown numerous time that witches can still perform feats of magic while on the Other Side as spirits. Such as the burial ground witches, they performed magic by channeling their own death spot. However it has been shown that powerful witches can directly affect change through the use of their personal Talismans, such as Esther Mikaelson in Ghost World. Witch spirits are also capable of using their powers as seen in Graduation when made manifest; this was only made possible because Bonnie hadn't put the veil back up.
 * Hunter Abilities: If a Supernatural Hunter becomes a ghost, they will still possess their hunter powers.

Weaknesses

 * Isolation: Ghosts can interact with the living through mediums and witches. However, if the person chooses to isolate themselves from the ghost, they will be forced to vanish.
 * Magic: Ghosts are susceptible to the forces of witchcraft. Because the other side was destroyed by a magic spell, all the ghosts who couldn't come back to life got sucked into the dark void or found peace.

Former Weaknesses

 * Doppelgänger Blood Magic: If blood from the last pair of doppelgängers are used in the Magic Purification Spell, all ghosts will be forced into Hell or find Peace.

The Other Side
The Other Side was the mysterious dimension where the spirits of dead supernatural beings reside. It was created by Qetsiyah in an attempt to imprison the immortal Silas. The spell ensured that every supernatural being that died would go to the Other Side, instead of the peaceful human afterlife.

Spirits on the Other Side could, during moments where the Veil was down, manifest themselves as Ghosts. They were able to interact, and cause harm, to those on the physical plane.

After the destruction of the the Other Side, the spirits were transported to various other dimensions that remain unknown.