ICANN Acronyms and Terms

ICANN has hundreds of acronyms and terms, which can be confusing. We created this multilingual tool to help explain what these terms mean and facilitate your work within the ICANN community.

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ICANN Acronyms and Terms

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Technical Experts Group(TEG)

A body within ICANN that focuses on forward-looking technical and technological issues. The TEG primarily addresses how issues with the Internet's system of unique identifiers affect the strategies and operations of the ICANN Board and the ICANN organization.

The TEG meets at ICANN Public Meetings with ICANN Board members and other invited participants. Meeting agendas focus on forward-looking issues to aid the Board in making informed strategic decisions.

Technical Liaison Group(TLG)

A body within ICANN that connects the ICANN Board with appropriate sources of technical advice on matters pertinent to ICANN's activities. The TLG consists of four organizations, each of which can appoint two representatives to the group:

  • European Telecommunications Standards Institute (ETSI)
  • International Telecommunications Union's Telecommunication Standardization Sector (ITU-T)
  • World Wide Web Consortium (W3C)
  • Internet Architecture Board (IAB)
  • All TLG participants are also members of ICANN's Technical Experts Group (TEG).

    temporary policy

    A short-term policy or specification that the ICANN Board of Directors can institute when it determines that an immediate action is necessary to maintain the stability or security of registrar services, registry services, the Domain Name System, or the Internet.

    thick record

    Registries satisfy their Registry Registration Data Directory Services (RDDS) obligations using different delivery services depending upon their contract terms. Thick registries maintain records of the registrant’s contact information and designated administrative and technical contact information, in addition to the sponsoring registrar, status of the registration, as well as creation and expiration dates for each registration.

    Examples of thick registries include .info and .biz.

    thin record

    Registries satisfy their Registry Registration Data Directory Services (RDDS) obligations using different delivery services depending upon their contract terms. A thin registry only includes records of technical data sufficient to identify the sponsoring registrar, status of the registration, as well as creation and expiration dates for each registration in its registration database.

    Examples of thin registries include .com and .net.

    time to live(TTL)

    A numeric value in a resource record that indicates the length of time (in seconds) a resolver can keep the resource record in its cache. If a resolver queries its cache and receives a record whose TTL has elapsed, the resolver requests a new copy of the record from an authoritative name server.

    top-level domain(TLD)

    A domain at the top of the naming hierarchy of the Domain Name System. In a domain name, the TLD appears after the second-level domain. For example, in the domain name icann.org, the characters org identify the TLD.

    The administrators of a TLD control which second-level domains are recognized within the TLD. TLDs fall into two classes: generic top-level domains (e.g., .com, .net, .edu) and country code top-level domains (e.g., .jp, .de, .in).

    Top-Level Domain (TLD) Application System(TAS)

    In the New Generic Top-Level Domain Program (New gTLD Program), the online interface that applicants use to submit applications for gTLDs to ICANN.

    trademark claims notice

    An automatic alert sent to trademark holders when someone attempts to register a domain name already matching a holder’s trademark in the Trademark Clearinghouse.

    Trademark Claims Period

    In the New Generic Top-Level Domain Program (New gTLD Program), a period that follows the Sunrise Period and runs for at least the first 90 days of general registration in a new gTLD.

    During the Claims Period, registrants are alerted in real time if they attempt to register domain names that match trademarks in the Trademark Clearinghouse (TMCH). If the registrant chooses to proceed with the registration after receiving the alert, the Claims Service notifies the holder of the trademark.

    Trademark Clearinghouse(TMCH)

    A mechanism of the New Generic Top-Level Domain (gTLD) Program designed to help protect the rights of trademark holders. The Trademark Clearinghouse verifies and records rights information from all over the world. This verified information is used during domain name registration processes, especially when new gTLDs launch.

    Trademark Clearinghouse Requirements

    A set of requirements related to the Trademark Clearinghouse (TMCH) that are specified in the Registry Agreement. These requirements define the mechanisms that a new generic top-level domain registry operator must have in place to support the rights protection services provided by the TMCH.

    Trademark Post-Delegation Dispute Resolution Procedure(Trademark PDDRP)

    In the New Generic Top-Level Domain Program (New gTLD Program), a formal procedure that generally addresses a registry operator's alleged complicity in trademark infringement on the first or second level of a new gTLD.

    Disputes resolved by a Trademark PDDRP are administered by Dispute Resolution Service Providers approved by ICANN. Complainants are required to take specific steps to address their issues before filing a formal complaint. An expert panel determines whether a registry operator is liable and recommends remedies to ICANN.


    The process of moving responsibility for a delegation of a resource from one entity to another. In the context of the Domain Name System (DNS) root zone, it involves assessing potential changes to top-level domains in the DNS against the applicable policies. This process was historically known as a redelegation.

    transfer contact

    An individual who is authorized to transfer a domain name to another registrar. A domain name’s registrant and administration contact are each recognized as transfer contacts.

    Transmission Control Protocol/Internet Protocol(TCP/IP)

    The pair of protocols that most major applications use to communicate over the Internet. TCP and IP work in tandem to provide reliable delivery of data between applications running on host systems connected to a network. During an Internet transmission:

    • IP breaks the sender’s data into small pieces called packets and relays the packets across the Internet based on the IP address in the packet header.
    • TCP establishes a connection between the applications and ensures that the sender’s data is delivered, error-checked, and reassembled in the proper order on the receiving end.

    Transport Layer Security(TLS)

    A cryptographic protocol that enables applications to communicate over the Internet in a way that helps prevent eavesdropping, message tampering, and forgery.

    TLS is the replacement for the Secure Sockets Layer (SSL) protocol, which has been deprecated by the Internet Engineering Task Force.

    trust anchor

    A verified cryptographic certificate that can be used to validate a chain of trust. For the Domain Name System (DNS), this is a signature of the key signing key for the root zone.

    Trusted Community Representative(TCR)

    A trusted member of the Domain Name System’s technical and operational communities who has been selected to maintain custody of materials required for the successful operation of the root zone key signing key (KSK). By design, access to the KSK is spread across many individuals who must come together to operate the key. The TCRs play an essential role in securing the KSK and maintaining trust in the Domain Name System Security Extensions mechanism.