Relational Algebra is a Procedural query language that takes two relations as input and produces another relation as an output of the query.

What is Relational Algebra?
Relational Algebra is a procedural query language that is used to operate on relational databases. It provides a set of operations that can be performed on relations or tables to retrieve desired information. Relational Algebra is a theoretical foundation for relational databases and is used as a basis for the design and implementation of relational database management systems (RDBMS).

Types of Query Languages
There are different types of query languages used in database systems, including:
1. Relational: Relational Algebra is a type of relational query language that operates on relations.
2. Structural: Structural query languages focus on the structure of the query rather than the specific operations performed on the data.
3. Procedural: Procedural query languages specify the step-by-step procedure to be followed to obtain the desired results.
4. Fundamental: Fundamental query languages are the basic languages used to interact with databases.

Characteristics of Relational Algebra
Relational Algebra has the following characteristics:
1. Set-oriented: Relational Algebra treats relations as sets of tuples and performs set operations such as union, intersection, and difference.
2. Closed: The result of any operation in Relational Algebra is always a relation.
3. Procedural: Relational Algebra specifies the order in which operations are executed to obtain the desired results.
4. Formal: Relational Algebra is based on a formal system of rules and principles.

Relational Algebra Operations
Relational Algebra provides several operations to manipulate relations. Some of the commonly used operations include:
1. Selection: Selects rows from a relation that satisfy a given condition.
2. Projection: Selects specific columns from a relation.
3. Union: Combines two relations to form a new relation that includes all tuples from both relations.
4. Intersection: Retrieves tuples that are common to two relations.
5. Difference: Retrieves tuples from one relation that are not present in another relation.
6. Join: Combines tuples from two relations based on a common attribute.

Conclusion
Relational Algebra is a procedural query language used to operate on relational databases. It takes two relations as input and produces another relation as the output of the query. Relational Algebra provides a set of operations to manipulate relations and retrieve desired information from databases. It is an essential component of relational database management systems and forms the foundation for designing and implementing database systems.