What are the Formal Sciences?

Formal science is a branch of knowledge related to formal systems, such as logic, mathematics, theoretical computer science, information theory, systems theory, decision theory, statistics, and some semantics. Unlike other sciences, formal sciences are not linked to the validity of theory based on real-world observations. And linked to the nature of formal systems based on definitions and laws. But formal science methods are used to build and test scientific models that observe the real world.