X (named ex , plural exes) is the 24th letter in the modern English alphabet and the ISO basic Latin alphabet.

The .x file extension was introduced with DirectX 2.0 to contain files of the X file format; and DirectX 6.0 introduced methods that enable reading from and writing to .x files.

AmiExpress - also known as /X - by Synthetic Technologies was a popular BBS software application for the Commodore Amiga line of computers. AmiExpress was extremely popular among the warez scene for trading (exchanging) software.

An emoticon ( or ), etymologically a portmanteau of emotion and icon, is a metacommunicative pictorial representation of a facial expression that, in the absence of body language and prosody, serves to draw a receiver's attention to the tenor or temper of a sender's nominal non-verbal communication, changing and improving its interpretation. It expresses — usually by means of punctuation marks (though it can include numbers and letters) — a person's feelings or mood, though as emoticons have become more popular, some devices have provided stylized pictures that do not use punctuation.

In mathematics, the factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example,

The voiceless uvular fricative is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is (or more properly ), or in broad transcription  although the latter technically represents a velar pronunciation. The sound is represented by (ex with underdot) in Americanist phonetic notation.

X is the twenty-fourth letter of the Latin alphabet.

See X2 (roller coaster) for the steel roller coaster formerly known as X operating at Six Flags Magic Mountain in Valencia, California, USA.

X (formerly known as X:\ No Way Out) is an indoor roller coaster located at Thorpe Park, England. It was the park's first non-powered roller-coaster. It is themed around a rave and has the strapline "Ride on a wave of light and sound".

X^ is the Latin letter X with a circumflex. The letter is used in the Haida language and Aleut languages of Alaska.