Khmer is a language spoken throughout southeast Asia, particularly in the nation of Cambodia. It is spoken by more than 20 million people, with the majority speaking it as a native language. Khmer is part of the Austro-Asiatic family of languages, and is related to languages such as Vietnamese and Mon.

Khmer is an official language of Cambodia. The region that is present-day Cambodia was once the center of the Khmer empire, from which the Khmer language originates. There are another estimated 5 million people who speak Khmer living in Vietnam and Thailand. Overseas, both France and the United States have large Cambodian immigrant populations who also speak Khmer, adding approximately 250,000 more speakers.

As the state religion of the Khmer Empire switched between Hinduism and Buddhism, the language also changed accordingly. During the Hindi periods, the Khmer language experienced a great deal of shift and vocabulary expansion from the Pali language used in the national religion, and during the Buddhist periods, it experienced similar growth through Sanskrit. Khmer has also been influenced as a language by the Lao and Thai languages, as well as a number of smaller languages existing in the same dialect continuum. A number of words and sentence structures seem to be derived from Lao or Thai forms, and both Lao and Thai are also heavily influenced by Khmer. One dialect of Khmer, known as Northern Khmer, is so different from standard Khmer that it is classified by some as a distinct language – this is due in large part to the fact that it is the dialect spoken in Thailand, and so has been even more heavily influenced by Thai, resulting in some extreme variations.

The modern Khmer alphabet is a descendent of the ancient Khmer alphabet, which has been in use for more than 1400 years, making it one of the oldest alphabets in southeast Asia. It consists of 33 consonants, 14 independent vowels, and 21 vowel diacritics. Each of the vowel diacritics may be used in one of two distinct series, effectively doubling the amount of vowel sounds they can make.

Khmer is considered much easier to learn for native English speakers than any of the major surrounding languages, such as Vietnamese, Lao, or Thai. While some of this is attributable to the grammar and vocabulary of Khmer, it is mostly a feature of Khmer being a non-tonal language. Most Asian languages present a great deal of difficulty to English speakers because of the need to switch into a mindset in which the tone of a word affects its meaning; Khmer has no such tonal structure, allowing for much easier acquisition.