Teh is a common typo for the. This misspelling of the most common word in the (written) English language is so common that it is one of the words in the auto-correct lists of spellcheckers in popular word processing applications, such as Microsoft Word, OpenOffice, or Corel WordPerfect.

In the online slang known as Leet, it is deliberately used in place of the, and often spelled with a numeral 3 in place of e. Teh and t3h are the traditional spellings of the in the phrase "ph33r t3h ...".

Besides being an alternate spelling of the, teh also has grammatical properties not generally applied to the. It can be used with proper names, as in "teh John"; compare the usage of the definite article in Greek: ο Ιωαννης, literally "the John". A similar usage comes from German, where the definite article is used as a specifier to modify the noun: "Der Johann", again literally, "the John", could be used to identify John, and not Phil, as the subject performing a certain action.

In English, the can be used as an intensifier for the superlative form of adjectives; cf. "that is best" and "that is the best". Teh has a similar use as an intensifier for unmodified adjectives, generally marking a sarcastic tone. For example, "that is teh lame" translates as "that is the lamest". This contrasts with the use of the in English to construct mass nouns from adjectives, as in "blessed are the meek", where the meek denotes a class of people who are meek.

Teh can also be used as an expletive (the origin of which is unknown) for embarrassment or annoyance at a mistake or accident, in place of more colorful language. It is sometimes accompanied by a hand gesture touching the thumb and middle finger to make an "O", or the middle finger alone to form what is fondly known in slang as "teh finger".

Sometimes, one just makes a mistake spelling the word. Either it's not noticed (and Microsoft Word's auto correcter encourages this). Or it isn't worth going back to change two letters, when everyone knows what was intended, for example: "I need to go to teh store.".