SQL, a relational language designed to manipulate data declaratively, has become the most successful 4th generation language. It was introduced in the 1970s by Don Chamberlin and Raymond Boyce, based on the foundation of relational algebra with the goal of providing an English-like query language. Over time, SQL has been extended and adapted to various technologies such as object databases, NoSQL, and big data formats. Despite the rise of alternative languages like Python and Java, SQL remains widely used due to its declarative nature, ability to be composed, and malleability. Its independence from data representation allows it to be used on non-relational data formats, making it a versatile language for data processing. The success of SQL can be attributed to its support for complex data models, new ideas, and extensions for various use cases, as well as its ability to optimize performance through cost-based optimizers and rich SDKs.