The main function of relational databases is to store, manage, and retrieve data efficiently using a structured format. They organize data into tables, which consist of rows and columns that represent records and attributes, respectively. This tabular format facilitates easy querying and manipulation of data through SQL (Structured Query Language). Relational databases ensure data integrity and reduce redundancy by establishing relationships between tables. They are widely used in various applications, from enterprise systems to web applications, providing a systematic approach to handling large volumes of data while ensuring quick access and consistency.