The transformation of a string of characters into a usually shorter fixed-length value or key that represents the original string. Hashing is used to index and retrieve items in a database as it is faster to find the item using the hashed key.

A tag used to categorize posts on Twitter (tweets) according to topics. It is done by prefacing the relevant term with the hash symbol (#). That will allow people who follow that topic to find your tweet and perhaps follow you as well. 

Haskell is a standardized, general-purpose purely functional programming language, with non-strict semantics and strong static typing.

HDSL is one of the earliest forms of DSL, used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that it is symmetrical.

A television display technology that provides picture quality similar to 35 mm movies with sound quality similar to that of today's compact disc. Some television stations have begun transmitting HDTV broadcasts on a limited number of channels. 

Headphones (or "head-phones" in the early days of telephony and radio) are a pair of small loudspeakers that are designed to be held in place close to a user's ears. They are also known as earspeakers, earphones or, colloquially, cans. The alternate in-ear versions are known as earbuds or earphones.

Heartbleed is a programming error (a.k.a bug) in the Open SSL code used by two thirds of the websites to protect customer/consumer information from hackers. Open SSL is used to transfer data between two devices over a secured line. The vulnerability lies on the servers that processes and transmit secure information.

In the OSPF communications protocol which enables network routers to share information with each other, a HELLO packet is a special packet (message) that is sent out periodically from a router to establish and confirm network adjacency relationships. 

A simple program that, when run, displays the message: Hello World . Fittingly, the Hello World program has long been the new programmer's induction into a myriad of programming languages.

Heroku is a cloud platform as a service (PaaS) with base operating system is Debian. It is one of the first cloud platforms, and supported only Ruby programming language initially, but later added support for Java, Node.js, Scala, Clojure and Python and (undocumented) PHP and Perl.

HP is best known for its line of personal computer printers, has also long been a leader in mid-range computer systems. It was founded in 1939 by Stanford University grads, William R. Hewlett and David Packard.

A vector graphics language, a type of object-oriented language that represents images through the use of geometrical formulas. Vector graphics are more efficient than the alternative, raster graphics: they require less memory space for storage.

A telecommunication technology in which optical fiber cable and coaxial cable are used in different portions of a network to carry broadband content (such as video, data, and voice). 

Hibernate is a free and opensource java library used for object relational mapping. It provides a framework to map java classes with traditional relational database, so that you focus on objects of your application and not worry about how to store and find them later.

The proposed enhancement of Mobile Internet Protocol versions 6 (MIPv6) that is designed to reduce the amount of signaling required and to improve handoff speed for mobile connections. 

A policy-based management of file backup and archiving in a way that uses storage devices economically and without the user needing to be aware of when files are being retrieved from backup storage media.