What is the basic explanation for Schrödinger's cat?

It is about the uncertainty principle applied to quantum mechanics. Before you see the cat, all possibilities are available: 50-50 it is alive or dead. Once you "peek", you affect the quantum state and the measurement makes the result come 100% in one possibility: either dead or alive. This means that you cannot measure without affecting the quantum states.

That description is basically correct. The poison was activated by the decay of a certain radioactive isotope, and since quantum states are indeterminant until measured, quantum mechanically, the wave function that described the cat was a linear combination of wave functions that described the cat being alive and the cat being dead. This means that the cat is both alive and dead at the same time.

It should be noted, however, that Schrodinger did not take this result seriously and actually thought it was absurd. He used this result to show a certain inadequacy of the underlying mathematical formulation of quantum mechanics.

In quantum physics, the "act of observing" quantum phenomenom "changes" or "determines" the outcome of the experiment, so...

Until you open that box to "observe the cat," the cat is "either dead or alive," but the "actual opening of the box" is what "determines either way" the cat's existence, so...

Before you open that lid to observe the cat's state of being...

It's "both" dead AND alive at the same time...

Pretty spooky, huh?!?

the way Schroedinger's cat experiment work is by him putting a cat in side the box and the way it works is that the cat could just be made of pure waves or as a particle

keep in fact that the electrons and protons and neutrons all act as waves or particles

It's like opening a box with the crowbar inside it..

Cat's point of view would differ from an outsider's perspective :)

Heisenberg's uncertainty principle. You can't observe the object without effecting the result being observed.

this cat was it discussed on Big Bang Theory?

no idea