What is centralized database?

A database which resides all of its data centralized and on one machine or some machines which are connected together but looks one for the users looking from outside. And who ever wants to use data, he picks data from there and uses and saves again there.

Let's start with the basics of what a database is and a brief history of computing.
A database is tool for collecting and organizing information. Databases can store information about people, products, orders, or anything else. Many databases start as a list in a word-processing program or spreadsheet. As the list grows bigger, redundancies and inconsistencies begin to appear in the data. The data becomes hard to understand in list form, and there are limited ways of searching or pulling specific data out for review. Once these problems start to appear, it's a good idea to transfer the data to a database created by a database management system (DBMS).

Centralized Processing and\or Centralized Database -
Processing and maintainence performed in one computer or in a cluster of coupled computers in a single location. On this computer or cluster of computers is where the database managment system and the centralized database physically resides. Access to the computer is via "dumb terminals," which send only input and receive output or "smart terminals," which add screen formatting. All data processing is performed in the central computer.

Centralized processing evolved from the first computers in the 1950s, which were stand-alone with all input and output devices in the same room. Starting in the 1960s, terminals were added throughout a company's headquarters and branch offices, and each terminal was wired into the central machine, whether local or via a remote communications method.

The Terminals Became PCs
As personal computers and local area networks (LANs) proliferated in the 1980s and 1990s, terminals were replaced with PCs, which were made to function like a terminal with the addition of hardware and software. Users could run their own applications and still access the central computer as required.

By the 1990s, "client/server" architecture began to replace terminal access. Client PCs communicated with network servers via the local network rather than terminals hardwired to a central machine. Although there are still hardwired terminals in use, the predominant technology today is the local area network (LAN).

Centralized database concentrate at a single place or area. You can only get information/data at a certain place where the database has been stored. Not like decentralization where they can download/get information/data from the mother database through networking.