This tool shows the 1s, 2s, 2p, 3s, 3p and 3d orbitals of a hydrogen-like atom in three ways: electron cloud, cross section and radial distribution. Every dot in the cloud stands for one observation, so the denser the dots, the higher the chance of finding the electron there.
The colors are the sign of the wave function ψ. Blue is positive and orange is negative, and they swap across a node. The white dashed lines on the cross section are the nodes, where ψ is 0 and no electron is found. On the radial distribution the probability falls to 0 at that radius.
For a p orbital you choose the axis it points along from x, y and z, and for a d orbital the type from dxy, dx²−y² and dz². When you pick another orbital the dots do not vanish. They travel to their places in the new orbital, so you see how the shape changes.
Choose an orbital in the orbital panel on the left, then use the view panel to pick how it is shown and to switch rotation, axes, nodes and phase color on and off. Drag the figure to turn the electron cloud.