I'm confused about what x , {x}, and {{x}} means. Could someone clarify it for me please?

I think that,

x is a value
{x} is a set of consisting of a single value, x
and i have no idea what {{x}} means

But I don't think this right because I'm doing problems and I'm interpreting it wrong

2. Originally Posted by ixi
I'm confused about what x , {x}, and {{x}} means. Could someone clarify it for me please?
The symbol $x$ is an individual in some language (read universe).
The symbol $\{x\}$ is a set that contains $x$.
The symbol $\{\{x\}\}$ is a set that contains the set $\{x\}$.

3. Originally Posted by Plato
The symbol $x$ is an individual in some language (read universe).
The symbol $\{x\}$ is a set that contains $x$.
The symbol $\{\{x\}\}$ is a set that contains the set $\{x\}$.
thanks