The size of the pixel defines the resolution of the database. Keep in mind that the terms 'pixel' and 'resolution' refers in this context to the data characteristics and not to your computer screen. In raster models, the belonging of a pixel to a particular class depends on classification methods used. Virtually all grid remote sensed data has to be classified to be useful for further analysis. Some programs are able to automatically classify pixels, however, the expert knowledge and experience is very important in raster classification techniques.
Records normally correspond to individual spatial objects or entities.
A selection of files, often stored in the same hardware system and connected through relational links is called database . Remember, that in some GIS systems one coverage, which can consist of a number of files, can be also called database. Data can be also stored or entered through a computer program, however it is a common practice to separate data and programming contents into different files. If part of the word is reserved for storing an exponent of a number much bigger values can be stored in a given amount of memory. These types of numbers are called floating point or real numbers .