Skip to main content

P to Q


Portable Document Format (PDF) is a file format developed by Adobe Systems, and is used to capture files containing many desktop publishing applications, such as Word and Corel Draw, making the viewing of these files possible within the PDF file reader - Adobe Acrobat (

Plug in:

A plug in is defined as an extension of a particular software application, which provides the application with added capabilities. For example in Internet browsers plug ins add capabilities to aid in the viewing, hearing, or saving of specially formatted files (


PNG (Portable Network Graphics) is a losslessly compressed bitmap image format. PNG was created to both improve upon and replace the GIF format with an image file format that does not require a patent license to use. PNG is officially pronounced as "ping", but it is often just spelled out (


A polygon (literally "many angle") is a closed planar path composed of a finite number of sequential line segments. The straight line segments that make up the polygon are called its sides or edges and the points where the sides meet are the polygon's vertices (


A polyline is a specific computer graphic which is composed of one or more line segments. This line can be created simply be specifying the endpoints of each segment (


A point is a geographic element which has a position, defined by its coordinates, but which has no extension (

Pop up:

A pop up is a new browser window that displays when the visitor clicks on a hotlinked graphic or hyperlinked text. Pop up windows are often smaller than the existing browser window and display on top of the existing page the visitor is viewing. Because pop up windows are a popular advertising technique, some users install a program that turns this feature off in their browser. These programs are often referred to as "pop-up window killers" or "pop up blockers". On some websites including online GIS websites, however, pop up form an integral part of the system and it is advisable to turn off pop ups window killers for these sites or the full functionality of the site will not be visible to the user (

Projections (Map):

Map projections are used to flatten the curved Earth surface into a map. This process distorts distance information as one moves away from the centre of the flattened area. Particular projections as best used for particular areas, which reduce this distortion. Using an improper projection can create large distortions (

Proxy Server:

A proxy server is a mediator server that works between a client computer and a real server. Proxy Servers receive requests from clients and relays these to the real server, which returns the information back via the proxy server. Proxy servers can reply to clients by using stored information, thus reducing the bandwidth required to request a new task to the real server ().


The process of telling a particular programme what you would like to find via entering particular words or phrases into specific search applications (