Browse Definitions :
Definition

entity tag (ETag)

Contributor(s): Matthew Haughn

An entity tag (ETag) is an HTTP header used for Web cache validation and conditional requests from browsers for resources.

Etags use persistent identification elements (PIE) that have been tagged to the user’s browser. Although a user may remove HTTP cookies, ETags store the same information along with covert backup to reconstitute the data of deleted cookies.

 Most typically, ETags request Web resources on the condition that they have been updated since the user’s last visit to the site. For instance:

A user may visit a site featuring a background that changes every week. On the first visit in a new week, the browser checks the cache and, finding no image or an outdated one, downloads the current background and caches it. If the user had already visited the site that week, the browser would receive the return response that the image had not changed. In that case, the browser would use the local copy in the cache, saving bandwidth and speeding load time.

HTML5 local storage and cache cookies enabled through ETags are also one method used to respawn cookies. Respawning cookies are used by consumer tracking firms to address the issue of user deletion or denial of cookies. The practice can also be used to track users for other purposes, such as keeping tabs on hackers.

This was last updated in October 2014

Continue Reading About entity tag (ETag)

Start the conversation

Send me notifications when other members comment.

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

  • compliance audit

    A compliance audit is a comprehensive review of an organization's adherence to regulatory guidelines.

  • regulatory compliance

    Regulatory compliance is an organization's adherence to laws, regulations, guidelines and specifications relevant to its business...

  • Whistleblower Protection Act

    The Whistleblower Protection Act of 1989 is a law that protects federal government employees in the United States from ...

SearchSecurity

  • brute force attack

    Brute force (also known as brute force cracking) is a trial and error method used by application programs to decode encrypted ...

  • spyware

    Spyware is software that is installed on a computing device without the user's knowledge. Spyware can be difficult to detect; ...

  • ATM black box attack

    An ATM black box attack, also referred to as jackpotting, is a type of banking-system crime in which the perpetrators bore holes ...

SearchHealthIT

SearchDisasterRecovery

  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • warm site

    A warm site is a type of facility an organization uses to recover its technology infrastructure when its primary data center goes...

  • disaster recovery (DR) test

    A disaster recovery test (DR test) is the examination of each step in a disaster recovery plan as outlined in an organization's ...

SearchStorage

  • enterprise storage

    Enterprise storage is a centralized repository for business information that provides common data management, protection and data...

  • disk array

    A disk array, also called a storage array, is a data storage system used for block-based storage, file-based storage or object ...

  • optical storage

    Optical storage is any storage type in which data is written and read with a laser. Typically, data is written to optical media, ...

Close