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 or 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].
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.