In general terms, partitioning is logically dividing anything into multiple subgroups so that each subgroup can be identified independently and can be combined into a single partition. Let's understand what partitioning means in terms of RDBMS.
Partitioning is generally used to divide data into multiple logical file groups for the purpose of performance, availability, and manageability. When dealing with big data, the normal tendency of data is to be in terms of billions of records. So to improve performance of the database, it is better to divide data among multiple file groups. These file groups can be on a single machine or shared across multiple machines and identified by a key. These file groups are known as partitioned data.