Atomic orbitals are regions of space around an atomic nucleus that are inhabited by electrons. The visual and mathematical representations of atomic orbitals show all possible locations for an atom's electrons.
According to the Heisenberg Uncertainty Principle, it is impossible to predict an electron's exact location and momentum, so orbitals are used to show where an electron could be. There are four different types of atomic orbitals: s, p, d and f orbitals.
S orbitals are spherical and centered on the nucleus. They hold two electrons. P orbitals are peanut-shaped, with each side holding one electron. P orbitals are grouped in threes, for a total of six electrons, and are aligned along x, y and z axes with the nucleus at the center. D orbitals look like crossed peanuts and come in groups of five, holding a total of 10 electrons. F orbitals are very complex in shape and difficult to visualize. They come in groups of seven and hold 14 electrons.