What is Structured Query Language (SQL) primarily used for?

Structured Query Language (SQL) is primarily used for manipulating and managing data in relational databases. It serves as the standard language for querying, inserting, updating, and deleting data in these databases, which are organized in a structured format using tables. SQL allows users to perform various operations such as retrieving specific information, aggregating data, and establishing relationships between different data sets.

In the context of relational databases, SQL's powerful syntax enables users to interact with the data efficiently, ensuring that they can maintain, analyze, and retrieve valuable information as needed. This capability is essential for applications requiring data storage and retrieval, making SQL a fundamental tool for database management.

The other choices pertain to different aspects of technology and programming that do not directly relate to SQL's primary function. Designing user interfaces primarily involves front-end development skills, creating web applications encompasses both front-end and back-end development principles, and building operating systems involves low-level programming and system architecture work. Thus, while all these areas are critical to IT and software development, they do not align with SQL's specialized purpose in the realm of data management within relational databases.