The main architecture of a DBMS is an entity. An entity is information that you collect data for. An Entity is like a table. Inside the table of information, the rows are records and the columns are attributes. Therefore, a record is a collection of related attributes about a certain entity. So when the data is entered in the database, each unit of data is called a "record". Every single record is unique and it is further "broken down" (1) to a different number of fields which are also known as attributes. Having only data in a database is useless. The data must be related and organize in such ways to create useful information for companies.In order to associate data, relationships must be formed by either a one-to-many relationship, one-to-one or many-to-many relationship. One-to-many relationship means for example a person can play for one team but a team has many players. One-to-one relationship means that a girl has 1 boyfriend and the boy has 1 girlfriend. Many-to-many relationship means that each supplier supplies many different companies and the company has many suppliers. Besides the relationships, in order to make a relation, each record must have a primary key which becomes an foreign key in an attribute of another record. Examples of DBMS softwares are Microsoft Access, FoxPro and DataEase.
Source: 1- http://www.referenceforbusiness.com/encyclopedia/Cos-Des/Database-Management-Systems.html
2- http://www.mountainman.com.au/software/history/intro.html
3- http://www.opensplice.com/image-upload/DBMS_Connect6.jpg
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