A few questiosn about encoding

[Nick the Gr33k]

On 14/6/2013 1:14 μμ, Cameron Simpson wrote:
> Normally a character in a b'...' item represents the byte value
> matching the character's Unicode ordinal value.

The only thing that i didn't understood is this line.
First please tell me what is a byte value

> \x1b is a sequence you find inside strings (and "byte" strings, the
> b'...' format).

\x1b is a character(ESC) represented in hex format

b'\x1b' is a byte object that represents what?


 >>> chr(27).encode('utf-8')
b'\x1b'

 >>> b'\x1b'.decode('utf-8')
'\x1b'

After decoding it gives the char ESC in hex format
Shouldn't it result in value 27 which is the ordinal of ESC ?

 > No, I mean conceptually, there is no difference between a code-point
 > and its ordinal value. They are the same thing.

Why Unicode charset doesn't just contain characters, but instead it 
contains a mapping of (characters <--> ordinals) ?

I mean what we do is to encode a character like chr(65).encode('utf-8')

What's the reason of existence of its corresponding ordinal value since 
it doesn't get involved into the encoding process?

Thank you very much for taking the time to explain.
-- 
What is now proved was at first only imagined!