When the consonant is a plosive, the effect is of a simultaneous articulation of a labial consonant such as [p] or [b], and a velar consonant such as [k] or [g]. Written therefore as [kp] (voiceless) or [gb] (voiced) they are common in West African languages, but uncommon elsewhere in the world.
The term 'labiovelar' may also be used in a somewhat looser way to refer to labialized velar consonants, that is ones that are primarily a velar such as [k] or [g] but have a secondary rounding of the lips. These sounds, denoted [kw] and [gw], are more common across the world's languages.