Functions and Tables, Beginner projects to understand components

[Bill Kelsoe <wildbillkelsoe@...>]

Hello

My basic understanding of functions is that they do something with values stored in container variables. I want a full list of these functions to read up what are they and what they do. 

For example I guess print is a function. io.read waits user input until Enter is hit on keyboard. Like this. function math does arithmetic using operators like +, -,*,/ and I guess others which I dont know about too. io.write takes the value stored in a variable where io runs it or evaluates it using a function and shoots it on screen post processing. 

where can I read these functions in entirety and examples of their use? Same thing for tables. I know to start a table I use {} but what are its uses in the context of practicality in a program except data entry. 

Also the arbitrary so called type userdata which briefly I skimmed I dont know what is it used for or examples of its use.

Is there a source for all chapters in PIL where the mentioned definitions (array,value,function,metatable,etc..) are merged to form chunks explained head to toe? To the novice people like me? Beginners?

Many thanks

Adel