What is the meaning of $this

[hopdi]

I've seen some scripts contain \[code\]$this\[/code\] in a PHP script that has OOP, I never knew the meaning of it... like\[code\]$this->refresh();\[/code\]Perhaps explain to me what \[code\]$this\[/code\] refers to be...?But I do know that you cannot use it as a dynamic variable like \[code\]$this_is_a_variable\[/code\] but why can't use it as a dynamic variable?