Sound system
The Khoisan languages share some similarities in their extremely complex sound systems.

Vowels
Many of the Khoisan languages have five vowels /i/, /e/, /a/, /o/, /u/ which can be produced with additional features, such as nasalization, pharyngealization, and different voice qualities such as breathy and creaky voice, sometimes resulting in up to 40 different vowels.

Consonants

Clicks
The Khoisan languages are known for their use of click consonants, including dental, alveolar, alveo-palatal, lateral, and bilabial clicks. Sandawe and Hadza of Tanzania use dental, alveolar and lateral clicks. Despite speculations, the origin of Khoisan click consonants remains a mystery.

A dental click sounds like "tsk, tsk! " and is made by putting the tongue just behind the front teeth.
An alveolar click sounds like the popping of a cork made by putting the tongue just behind the ridge in back of the front teeth.
An alveo-palatal click is a sharp pop made by drawing the tongue down quickly from the roof of the mouth.
A lateral click sounds like the sound used in English to urge on a horse.
A bilabial click is a pop made by bringing the lips together and releasing them, just like the sound of a kiss.

Each click can be accompanied by voicing, nasality, aspiration, and ejection to produce a large number of different click combinations. The Khoisan languages differ in the number of such combinations from a low of 20 in Nama to a high of 83 in Kxoe. In addition, southern Khoisan languages show a very high ratio of words containing clicks as compared to those that do not.

Here is a table with all the clicks used in Nama (Wikipedia)

*A tenuis consonant is a voiceless unaspirated consonant, such as the [p] in Spanish or French that are produced without the puff of air that accompanies the English [p].

Other consonants
In addition to click consonants, the Khoisan languages use a large number of other consonants, up to a total of 90 consonants in |Gwi.

• Syllable shapes
  All click and most nonclick consonants appear at the beginning of words and are followed by a vowel. Only a few consonants, such as /b/, /m/, /n/, /r/, and /l/ can appear between vowels, and even fewer can appear at the end of words.

Tones
Khoisan languages feature several tones. For instance, Ju|'hoan has four level tones and one rising tone.

Click here to listen to a 1930 recording of Ikora, a now extinct language of South Africa.
Click here to listen to a folk tale in Nama (go to Languages>Nama>Folktale).

Click here to listen to a music CD from the San Bushmen of Namibia (lots of clicks!)

The word and sentence structure of Khoisan languages differ considerably, not just between the southern Khoisan languages and those of Tanzania, but also within the southern group itself.

Nouns
Most Khoisan nouns fall into three groups, based on gender: masculine, feminine, and common. In Kxoe, for example, genders in inanimate nouns are also associated with shape, e.g., masculine is associated with long, narrow objects, while feminine is associated with short, broad, round objects. Different endings are assigned to different genders, e.g., in the Nama language, khoe-b is "man" while khoe-s is "woman".

There are three numbers: singular, dual, and plural. They are controlled by noun gender.

Verbs
A grammatical feature common to many of the Khoisan languages is the use of verb compounds where English would use a preposition or a single verb, e.g., the equivalent of English enter is something like go+enter.

Word order
The usual word order is either Subject-Verb-Object, or Subject-Object-Verb, depending on the language.