Relational databases contain data organized in tables made of rows and columns, with each table column containing a specific data type. Transactions support ACID (Atomic, Consistent, Isolated, Durable) properties, assuring that all transaction are processed reliably.
Atomic means that if any part of the transaction fails, the entire transaction fails. All data is brought back to its state prior to the failed transaction.
Consistent means that everything written to the database must be valid according to all defined rules including constraints, cascades, and triggers.
Isolated means that the effects of a transaction are not visible to other transactions until the transaction is complete.
Durable means that all committed transactions are stored permanently and will persist even if there is a loss of power or the database crashes.