What is "path"

path \path\ (p[.a]th), n.; pl. paths (p[.a][th]z). [AS. p[ae][eth], pa[eth]; akin to D. pad, G. pfad, of uncertain origin; cf. Gr. pa`tos, Skr. patha, path. [root]2

1. ] 1. A trodden way; a footway.

   The dewy paths of meadows we will tread.
   --Dryden.

2. A way, course, or track, in which anything moves or has moved; route; passage; an established way; as, the path of a meteor, of a caravan, of a storm, of a pestilence. Also used figuratively, of a course of life or action.

   All the paths of the Lord are mercy and truth.
   --Ps. xxv. 10.

   The paths of glory lead but to the grave.
   --Gray.

Old English paþ, pæþ "path, track," from West Germanic *patha- (cognates: Old Frisian path, Middle Dutch pat, Dutch pad, Old High German pfad, German Pfad "path"), of uncertain origin. The original initial -p- in a Germanic word is an etymological puzzle. Don Ringe ("From Proto-Indo-European to Proto-Germanic," Oxford 2006) describes it as "An obvious loan from Iranian ..., clearly borrowed after Grimm’s Law had run its course." Watkins says the word is "probably borrowed (? via Scythian) from Iranian *path-," from PIE root *pent- "to tread, go, pass" (source of Avestan patha "way;" see find (v.)), but this is too much of a stretch for OED and others. In Scotland and Northern England, commonly a steep ascent of a hill or in a road.

n. A trail for the use of, or worn by, pedestrians. vb. (context transitive English) To make a path in, or on (something), or for (someone).

1. n. a course of conduct; "the path of virtue"; "we went our separate ways"; "our paths in life led us apart"; "genius usually follows a revolutionary path" [syn: way, way of life]

2. a way especially designed for a particular use

3. an established line of travel or access [syn: route, itinerary]

4. a line or route along which something travels or moves; "the hurricane demolished houses in its path"; "the track of an animal"; "the course of the river" [syn: track, course]

PATH may refer to:

• Partners for Advanced Transit and Highways, a research organization operated by the University of California
• PATH (global health organization), an international nonprofit organization in Seattle
• PATH (Toronto), a network of underground pedestrian tunnels in Toronto, Ontario, Canada
• PATH (variable), a computer operating system environment variable specifying a list of directories where executable programs are located
• PATH Foundation, a trail-building organization Georgia, USA
• PATH (rail system), officially the Port Authority Trans-Hudson, a subway system linking Manhattan, New York with locations in northern New Jersey
• Piedmont Access to Health Services, Inc. (PATHS), Healthcare Center
• Positive Alternatives to Homosexuality, a coalition of ex-gay organizations
• Potomac-Appalachian Transmission Highline, a proposed electrical line
• Professional Association of Therapeutic Horsemanship
• Projects for Assistance in Transition from Homelessness

The Port Authority Trans-Hudson, commonly called PATH, is a rapid transit system serving Newark, Harrison, Hoboken, and Jersey City in metropolitan northern New Jersey, as well as lower and midtown Manhattan in New York City. The PATH is operated by, and named after, the Port Authority of New York and New Jersey. PATH trains run 24 hours a day and 7 days a week.

The system has a route length of , not including any route overlap. In the third quarter 2015, PATH had an average weekday ridership of 263,300. PATH trains only use tunnels in Manhattan, Hoboken and downtown Jersey City. The tracks cross the Hudson River through century-old cast iron tubes that rest on the river bottom under a thin layer of silt. PATH's route from Grove Street in Jersey City west to Newark runs in open cuts, at grade level, and on elevated track.

While some PATH stations are adjacent or connected to New York City Subway, Newark Light Rail, Hudson-Bergen Light Rail, and New Jersey Transit stations, there are no free transfers between these different, independently run transit systems. PATH does accept the same pay-per-ride MetroCard used by the New York City Transit system, but it does not accept unlimited ride, reduced fare, or EasyPay MetroCards.

PATH, (formerly called the Program for Appropriate Technology in Health) is an international, nonprofit global health organization based in Seattle, with 1200+ employees in more than 30 offices around the world. Its president and CEO is Steve Davis.

PATH's tagline is "Driving transformative innovation to save lives".

PATH is an environment variable on Unix-like operating systems, DOS, OS/2, and Microsoft Windows, specifying a set of directories where executable programs are located. In general, each executing process or user session has its own PATH setting.

A path, the general form of the name of a file or directory, specifies a unique location in a file system. A path points to a file system location by following the directory tree hierarchy expressed in a string of characters in which path components, separated by a delimiting character, represent each directory. The delimiting character is most commonly the slash ("/"), the backslash character ("\"), or colon (":"), though some operating systems may use a different delimiter. Paths are used extensively in computer science to represent the directory/file relationships common in modern operating systems, and are essential in the construction of Uniform Resource Locators (URLs). Resources can be represented by either absolute or relative paths.

In graph theory, a path in a graph is a finite or infinite sequence of edges which connect a sequence of vertices which, by most definitions, are all distinct from one another. In a directed graph, a directed path (sometimes called dipath) is again a sequence of edges (or arcs) which connect a sequence of vertices, but with the added restriction that the edges all be directed in the same direction.

Paths are fundamental concepts of graph theory, described in the introductory sections of most graph theory texts. See e.g. Bondy and Murty (1976), Gibbons (1985), or Diestel (2005). Korte et al. (1990) cover more advanced algorithmic topics concerning paths in graphs.

PATH is a network of underground pedestrian tunnels, elevated walkways, and at-grade walkways connecting the office towers of Downtown Toronto, Ontario, Canada. It is more than long. According to Guinness World Records, PATH is the largest underground shopping complex in the world with of retail space.

The PATH network's northerly point is the Toronto Coach Terminal at Dundas Street and Bay Street, while its southerly point is Waterpark Place on Queens Quay. Its main axes of walkways generally parallel Yonge Street and Bay Street.

In mathematics, a path in a topological space X is a continuous function f from the unit interval I = [0,1] to X

The initial point of the path is f(0) and the terminal point is f(1). One often speaks of a "path from x to y" where x and y are the initial and terminal points of the path. Note that a path is not just a subset of X which "looks like" a curve, it also includes a parameterization. For example, the maps f(x) = x and g(x) = x represent two different paths from 0 to 1 on the real line.

A loop in a space X based at x ∈ X is a path from x to x. A loop may be equally well regarded as a map f : I → X with f(0) = f(1) or as a continuous map from the unit circle S to X

This is because S may be regarded as a quotient of I under the identification 0 ∼ 1. The set of all loops in X forms a space called the loop space of X.

A topological space for which there exists a path connecting any two points is said to be path-connected. Any space may be broken up into a set of path-connected components. The set of path-connected components of a space X is often denoted π(X);.

One can also define paths and loops in pointed spaces, which are important in homotopy theory. If X is a topological space with basepoint x, then a path in X is one whose initial point is x. Likewise, a loop in X is one that is based at x.

Path is a social networking-enabled photo sharing and messaging service for mobile devices that was launched in November 2010. The service allows users to share up to a total of 500 contacts with their close friends and family.

Dave Morin, co-founder and CEO, says: "Our long-term grand vision here is to build a network that is very high quality and that people feel comfortable contributing to at any time."

The company began with an iPhone application and a website. Later they released apps for Android, iPad, and Windows Phone. The company competes with other social networks such as Instagram. Path established innovations in UI design that continue through other mobile applications including context sensitive bubbles and the three bar menu slide.

Based in San Francisco, California, the company was founded by Shawn Fanning and former Facebook executive Dave Morin. Path's initial $2.5 million funding round included Ron Conway, Index Ventures, First Round Capital, Ashton Kutcher, Kevin Rose, Marc Benioff, Chris Kelly, and others. It subsequently raised $30 million in venture capital from Redpoint Ventures. On January 11, 2014, the company announced it had raised another $25 million in venture funding from Indonesian Bakrie Group, Kleiner Perkins Caufield & Byers, Index Ventures, Greylock Partners, Insight Venture Partners, Redpoint Ventures, and First Round Capital.

Indonesia is the world's largest Path userbase with more than 4 million users.

On May 28, 2015, Path announced it has been acquired by Daum Kakao.