Here's why:

* Opposite Charges Attract: The nucleus of an atom is positively charged due to the presence of protons. Electrons, on the other hand, carry a negative charge. Opposite charges attract each other.

* Centripetal Force: The electromagnetic force acts as a centripetal force, pulling the electrons towards the nucleus, keeping them in orbit.

* Quantum Mechanics: While the classical view of electrons orbiting the nucleus like planets around a star is simplified, the actual behavior is governed by quantum mechanics. Electrons exist in specific energy levels and orbitals around the nucleus, governed by complex probability distributions.

In essence, the electromagnetic attraction between the positively charged nucleus and the negatively charged electrons is the fundamental force that binds the atom together.