What Does ψ_0(x) = <x|0> Represent in Dirac Notation?

[AverageHuman]

Do not solve the problem just look at the picture.

http://i208.photobucket.com/albums/bb33/DanusMax/giro2_zps11d2056b.jpgWell its the end of the semester and I found out that I had only one of the required books for my undergraduate course.

Anyways back to the question. As you can see in the photo what I would like to know is what
ψ_0(x)= <x|0>. stands for?

I haven't seen examples of how to use it or anything. I do know that it can be broken up and something can be placed in the center <x|?|0>.

what i don't know is what that x is or why there's a zero on the other side. What does it mean I would like to have examples if possible.

 

[MisterX]

The $\mid 0 \rangle$indicates the ground state. The $\langle x\mid$ is the bra for "x" basis state, which is the state associated with the position x.