ASCII 64 — @

The at sign is universally recognized as the separator in email addresses ([email protected]), a convention established by Ray Tomlinson in his 1971 implementation of ARPANET email. In programming, '@' serves diverse purposes: Python uses it for function and class decorators, Java for annotations, CSS for at-rules like @media and @import, and Ruby and Objective-C for instance variable prefixes. On social media platforms, '@' mentions or tags other users. The symbol's origin may trace back to a medieval Latin abbreviation for 'ad' meaning 'at' or 'toward'.

Symbol characters in ASCII include mathematical operators, logical notation, and special-purpose marks that serve critical roles across programming, mathematics, and digital communication. Symbols are heavily context-dependent — the same character may act as an arithmetic operator in one language, a regex metacharacter in another, and a shell configuration flag in a third context. This contextual polyvalence makes symbols among the most functionally overloaded characters in computing, requiring careful attention to their meaning in each domain.

In the ASCII encoding table, At Sign is assigned code point 64 in decimal (0x40 hexadecimal, 100 octal, 01000000 binary). The 7-bit ASCII standard, first published in 1963 by the American Standards Association, defines exactly 128 characters that remain the foundation of text encoding systems worldwide. UTF-8, the dominant encoding on the modern web, is fully backward compatible with ASCII — every ASCII character is encoded as the identical single byte in UTF-8, guaranteeing that At Sign works reliably across all operating systems, programming languages, and internet protocols.