The relational data model organises information in the form of one or more tables. The name originates from the technical designation "relations" for tables. The rows of a table can be called "data set" or "tuple"; instead of columns, one also speaks of "fields", "attributes" or "properties". A table can, at least theoretically, have an unlimited number of rows and columns. An existing table can be extended at any time with new rows as well as new columns. A collection of several tables can be called a database. For the administration of such a collection of tables/database, so-called database management systems (DBMS) are used, like, e.g., MySQL or PostgreSQL. The administration of the data as well as its analysis is carried out by means of a specific formal language, the so-called Structured Query Language (SQL), which was specially developed for use with data in the relational format and is available in a version standardised by the ISO (Wikipedia).
There are special rules for displaying information in the relational data model, which, in fact, are a science in their own right (e.g., the so-called database normalisation). At the same time, the concrete choice of modelling is not dependent on the application and compliance with existing modelling rules is, in some cases, rather obstructive from the perspective of usability and performance. In practice, all data modelling represents a compromise between the specifications of the theoretical set of rules, technical requirements and user-friendliness. Moreover, once a data model has been chosen, it can be modified at any time and adapted to changing requirements.