Warlock

Warlocks are an evil race of magical beings that hunt, capture and kill witches for power. They are known to be ex-witches who have evolved into beings of pure Darkness through years of dedication to Evil in a manner comparable to how Good witches and Whitelighters are dedicated to Good. The term is not gender-specific and refers to witches who have gone down the path of evil, rescinding their humanity after committing an irrevocable act of evil – where one of their selfish main goals are to expand their own powers by killing witches and stealing their powers.

Powers and Abilities
Warlocks will often acquire the powers of witches they kill by absorbing their magical essence, therefore, a warlock will have all the basic powers of the witch i.e. Scrying, Potion brewing, Spellcasting etc. However they tend not to use these in favour of their active powers.

A common warlock ability is a form of teleportation called Blinking. The ability is so prevalent in the warlock population that the Halliwells will assume that anyone with this power is a warlock.

Although Blinking is associated with all Warlocks, they have about the same variety of powers that witches do, although an individual Warlock is likely to possess a greater number of powers than any individual witch. In the course of the series, warlocks have demonstrated a large number of powers acquired through hunting and murdering witches, including Fire Balls, astral projection, pyrokinesis, telekinesis, freezing time, Glamouring, Cloning, Super human strength, Transformation and Knowledge Absorption.

Becoming A Warlock
There are two ways for a witch to become a warlock:

The first is for the witch to use his or her powers to kill another witch and take his or her powers.

Second is for a magical witch to be married to a warlock in a dark binding ceremony comparable to Handfasting. The witch's consent is not required, and when the ritual is complete, the new warlock will be Evil, despite his or her previous moral inclinations.

Good Witches can also become warlocks by turning evil either by choice or force such as with the dark binding ceremony. They must complete the transformation in the same manner, by the killing of an innocent. Until then they may be easily influenced by the other side. Two warlocks can produce a child, that will automatically be a warlock. It also seems possible that a warlock born as such with two warlock parents may too turn good.

Blood
Warlocks are not considered demons either by witches or demons. Warlocks are said to be inherently and irredeemably evil, and are said not to bleed.
 * A possible reason why some warlocks bleed while others do not could be based on their heritage; a warlock who is half human will bleed due to human half, a full blooded warlock or spawn of two warlock parents will not bleed due to lack of humanity.