How do you free up memory in C?

I'm curious to know, how exactly does one go about freeing up memory in the programming language C? It's a common concern for developers working with C, given its manual memory management. Are there specific functions or techniques that you recommend to effectively deallocate memory that's no longer needed, in order to avoid memory leaks and ensure efficient use of resources? It would be great if you could elaborate on the process and any best practices to keep in mind.