ATM (or atm) is an abbreviation and term used in different fields. Depending on context and capitalization it can refer to several distinct concepts, listed and explained below.

Automated teller machine

Most commonly, ATM stands for automated teller machine: an electronic device that provides customers of banks and financial institutions with access to basic banking services, such as cash withdrawals, deposits, balance inquiries, and transfers, without the need for a teller. ATMs became widely available beginning in the 1960s and remain a key part of retail banking infrastructure worldwide.

Unit of pressure: atmosphere (atm)

The lowercase atm is the symbol for the standard atmosphere, a unit of pressure defined as exactly 101325 pascals (Pa). It is used to express pressures roughly equivalent to average sea‑level atmospheric pressure and appears in disciplines such as chemistry, physics, and engineering.

Telecommunications: Asynchronous Transfer Mode

In networking, ATM refers to Asynchronous Transfer Mode, a packet-switching technology that carries data in fixed-size cells and was developed to support integrated voice, video, and data services with quality-of-service mechanisms. ATM was widely deployed in backbone and carrier networks in the 1990s and early 2000s; newer IP-based approaches and MPLS have since replaced much of its role, though ATM equipment and standards remain in use in some environments.

Biology: ATM gene and protein

In molecular biology, ATM denotes the gene that encodes the ATM protein kinase (Ataxia Telangiectasia Mutated). This protein plays a central role in the cellular response to DNA damage, coordinating repair, checkpoint control, and cell-cycle regulation. Pathogenic variants in ATM can cause the inherited disorder ataxia–telangiectasia and increase cancer risk.

Finance: at-the-money (ATM)

In options trading, ATM is shorthand for "at the money," describing an option whose strike price is equal (or very close) to the current price of the underlying asset. This contrasts with "in the money" and "out of the money" options, which have intrinsic value or do not, respectively.

Other common uses

  • atm as internet slang: an abbreviation of "at the moment," frequently used in informal text and social media.
  • ATM as an acronym in aviation and transport: used for phrases such as "air traffic management" to refer to systems and procedures that ensure safe and efficient aircraft operations.

Because ATM appears across many disciplines, the intended meaning depends on subject matter and capitalization. When encountering the term, consider the surrounding context to determine which definition applies.