Laterals are "L"-like consonants pronounced with an occlusion made somewhere along the axis of the tongue, while air from the lungs escapes at one side or both sides of the tongue.
Most commonly the tip of the tongue makes contact with the upper teeth (see dental consonant) or the upper gum (the alveolar ridge) just behind the teeth (see alveolar consonant). Most laterals are approximants and belong to the class of liquids.
English has the alveolar lateral [l], which in many accents has two allophones. One, found before vowels as in lady or fly, is called clear [l], pronounced with a "neutral" position of the body of the tongue. The other variant, so-called dark [l] found before consonants word-finally as in bold or tell, is pronounced with the tongue assuming a spoon-like shape and its back part raised, which gives the sound an [u]-like resonance.
In many British accents (e.g. London English), dark [l] may undergo vocalisation through the reduction and loss of contact between the tip of the tongue the alveolar ridge, becoming a rounded back vowel or glide. This process turns tell into something like [tew].
The Italian gl and Spanish ll (in some accents) are palatal laterals. The palatal lateral is present as well in these languages: Catalan ll, French ill- (in some dialects), Portuguese lh, Quechua ll.
Rarer lateral consonants include the sound of Welsh ll, which is a voiceless lateral fricative, and the retroflex laterals as can be found in most Hindustani languages.
Many non-Indo-European languages (e.g. in several native language families of North America and aboriginal Australian ones) have whole systems of several different lateral fricatives and affricates in their consonant inventories.
List of laterals