A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger geographic distance, but also generally involves leased telecommunication circuits.
Ethernet and Wi-Fi are the two most common technologies in use for local area networks. Historical network technologies include ARCNET, Token Ring, and AppleTalk.
A laptop (also laptop computer), often called a notebook, is a small, portable personal computer (PC) with a “clamshell” form factor, typically having a thin LCD or LED computer screen mounted on the inside of the upper lid of the clamshell and an alphanumeric keyboard on the inside of the lower lid. The clamshell is opened up to use the computer. Laptops are folded shut for transportation, and thus are suitable for mobile use. Its name comes from lap, as it was deemed to be placed on a person’s lap when being used. Although originally there was a distinction between laptops and notebooks (the former being bigger and heavier than the latter), as of 2014, there is often no longer any difference. Today, laptops are commonly used in a variety of settings, such as at work, in education, for playing games, Internet surfing, for personal multimedia, and general home computer use.
Large-screen television technology developed rapidly in the late 1990s and 2000s. Various thin screen technologies are being developed, but only the liquid crystal display (LCD), plasma display (PDP) and Digital Light Processing (DLP) have been released on the public market. A video display that uses large-screen television technology is called a jumbotron. These technologies have almost completely displaced cathode ray tubes (CRT) in television sales, due to the necessary bulkiness of cathode ray tubes. However, recently released technologies like organic light-emitting diode (OLED) and not-yet released technologies like surface-conduction electron-emitter display (SED) or field emission display (FED) are making their way to replace the first flat screen technologies in picture quality. The diagonal screen size of a CRT television is limited to about 40 inches because of the size requirements of the cathode ray tube, which fires three beams of electrons onto the screen, creating a viewable image. A larger screen size requires a longer tube, making a CRT television with a large screen (50 to 80 inches) unrealistic because of size. The aforementioned technologies can produce large-screen televisions that are much thinner.
Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometers (nm), or 4.00 × 10−7 to 7.00 × 10−7 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). This wavelength means a frequency range of roughly 430–750 terahertz (THz).
In computing, a hyperlink, or simply a link, is a reference to data that the user can follow by clicking or tapping. A hyperlink points to a whole document or to a specific element within a document. Hypertext is text with hyperlinks. The text that is linked from is called anchor text. A software system that is used for viewing and creating hypertext is a hypertext system, and to create a hyperlink is to hyperlink (or simply to link). A user following hyperlinks is said to navigate or browse the hypertext.
Logical topology is the arrangement of devices on a computer network and how they communicate with one another. Logical topologies describe how signals act on the network.
In contrast, a physical topology defines how nodes in a network are physically linked and includes aspects such as geographic location of nodes and physical distances between nodes. The logical topology defines how nodes in a network communicate across its physical topology. The logical topology can be considered isomorphic to the physical topology, as vice versa.
Early twisted pair Ethernet with a single hub is a logical bus topology with a physical star topology. While Token Ring is a logical ring topology with a physical star topology.
In telecommunications, Long-Term Evolution (LTE) is a standard for wireless broadband communication for mobile devices and data terminals, based on the GSM/EDGE and UMTS/HSPA technologies. It increases the capacity and speed using a different radio interface together with core network improvements. The standard is developed by the 3GPP (3rd Generation Partnership Project) and is specified in its Release 8 document series, with minor enhancements described in Release 9. LTE is the upgrade path for carriers with both GSM/UMTS networks and CDMA2000 networks. The different LTE frequencies and bands used in different countries mean that only multi-band phones are able to use LTE in all countries where it is supported.
LTE Advanced is a mobile communication standard and a major enhancement of the Long Term Evolution (LTE) standard. It was formally submitted as a candidate 4G to ITU-T in late 2009 as meeting the requirements of the IMT-Advanced standard, and was standardized by the 3rd Generation Partnership Project (3GPP) in March 2011 as 3GPP Release 10.
LTE Advanced Pro (LTE-A Pro, also known as 4.5G, 4.5G Pro, 4.9G, Pre-5G, 5G Project) is a name for 3GPP release 13 and 14. It is the next-generation cellular standard following LTE Advanced (LTE-A) and supports data rates in excess of 3 Gbit/s using 32-carrier aggregation. It also introduces the concept of License Assisted Access, which allows sharing of licensed and unlicensed spectrum.
Additionally, it incorporates several new technologies associated with 5G, such as 256-QAM, Massive MIMO, LTE-Unlicensed and LTE IoT, that allow evolution of existing networks into supporting the 5G standard.