Geotagging & it's applications

Geotagging is the process of adding geographical identification metadata to various media such as photographs, video, websites, or RSS feeds and is a form of geospatial metadata. These data usually consist of latitude and longitude coordinates, though they can also include altitude, bearing, distance, etc.

It is sometimes also called geocoding, geotagging is the process of assigning geographic location metadata to a photos' EXIF data (which normally would only contain details about the digital camera being used to take the photo). ...

Uses:

• can help users find a wide variety of location-specific information. For instance, one can find images taken near a given location by entering latitude and longitude coordinates into a geotagging-enabled image search engine. Geotagging-enabled information services can also potentially be used to find location-based news, websites, or other resources
  
• A geocoded photograph, a term that more often refers to the process of taking non-coordinate based geographical identifiers, such as a street address, and finding associated geographic coordinates (or vice versa for reverse geocoding), or to the use of a camera that inserts the coordinates when making the picture, for example using its built in GPS receiver.

There are multiple ways of Geo Tagging. But most latest cameras have this feature build in. Photos can be also be Geo Tagged manually. HTML pages and Blogs can also be tagged.

Geotagging photos using GPS
Because of the requirement for wireless service providers to supply more precise location information for 911 calls by September 11, 2012, more and more cells phones have built in GPS chips. Some cell phones like the iPhone and Samsung Memoir already utilize a GPS chip along with built-in cameras to allow users to automatically geotag photos. A few cameras such as the Ricoh 500SE and the Sony DSC-HX5V have built-on or built-in GPS that allow for automatic geotagging. Nikon and Canon have also come out with custom geotagging solutions. Almost any digital camera can be coupled with a GPS and post processed with photo mapping software such as GPS-Photo Link, MediaMapper, Topofusion or EveryTrail GPS Connector (for Garmin gps products) to geotag photos by matching gps coordinates with photos. Twitter, the popular social networking and microblogging service that enables its users to send and read messages known as tweets, allows its users to geotag their locations via their tweets and pictures.

Source: http://en.wikipedia.org/wiki/Geotagging