What are the 3 main functions of a network?

Can you elaborate on the three main functions of a network? As a curious individual interested in the intricacies of digital systems, I'm intrigued to understand how they operate at a foundational level. Are these functions crucial for facilitating communication, data transfer, and resource sharing? Or do they encompass other essential aspects that underpin the seamless functioning of modern networks? I'm particularly keen to know how these functions work in harmony to enable networks to serve their purpose effectively.