Schrödinger's famous thought experiment has come to be known as Schrodinger's Cat. Schrodinger's cat is kind of a parable about the idea of quantum superposition. Schrodinger was disturbed by the implications of quantum theories and apparent paradoxes.

In quantum mechanics he wanted to show how absurd quantum mechanics is. He came up with a thought experiment. This was the idea: you take a cat and you put it in a box completely isolated from everything on the outside. The box is fitted with a hammer and a beaker filled with cyanide and there's also a control mechanism. The box which is controlled by single atom which can undergo radioactive decay and when the atom decays, the detector activates the hammer, the file will be broken and the cyanide will be released. That is going to kill the cat and the cat will die. If it doesn't emit the particle, the poison is not released and the cat is alive.

Now suppose, say after an hour there is a 50% probability that the Geiger counter will have detected something. Until we look inside the possibility exists that the cat is either alive or dead and if we believe quantum mechanics then the cat at that point is in a state which is simultaneously dead and alive.

Schrodinger’s point was that it's absurd to think that the cat is somehow simultaneously dead and alive just because it's described by a superposition and so similarly we should reconsider how we think about electrons in superposition.

Since then there has been no general agreement among the physicists whether to take this idea of the cat being simultaneously alive and dead seriously. The important point is that superposition cannot be explained in terms of familiar classical concepts and this is exactly what makes quantum mechanics so intriguing.