Imagine you are standing in the middle of a football pitch. If you now close your eyes, and the game goes on, you don’t know the specific positions of the individual players. You can however make a good guess in which region specific players are located due to their roles, such as the striker, defender, midfielder,… The same is true for the positions of electrons. We can’t pinpoint an exact position, but we can mark regions where it is most likely to find an electron. For an 1s-electron specifically, this region looks like a spheric cloud around the nucleus.