Database is an organized collection of data, for example a library catalog (with alphabetical listing of all the available books). Databases help us in retrieving useful information easily. For example it is much easier to find a particular book in a library if we can get a database that contains alphabetically arranged listing of books. The databases are managed through software packages called "database management systems" (DBMS).
A database keeps all the information together and it can be easily moved around on a laptop or pen-drive or memory card. It stores a large amount of information in easily retrievable way. It can be accessed simultaneously by multiple users over a network and it can also be made very secure (using the relevant security protocols and applications).
However, they are complex, time-consuming and difficult to design and entail initial set up (hardware and software) cost as well as require user training. Another issue is the related to the safety of portable information, as we keep on hearing every few months how a laptop stolen at an airport compromised the financial information (bank account numbers, credit card information, etc.) of thousands of users.
One can create a database by using one of the many available DBMS options, including MySQL, Oracle, Microsoft SQL Server, IBM DB2, etc.