trying to understand UID and subkeys

[Felipe Alvarez]

Me again. Sorry to sound newbish. I've googled, but I haven't found anything
quite as detailed enough for me to grasp the 'whole forest' (so to speak).
My question is regarding 'subkeys.' Let me know if I am getting the
wording/terminology incorrect.

I understand that when I 'gen-key' I create a 'signing' key (to identify
tampering/modification) and an 'encryption' key (shouldn't this be a
DEcryption key? Wouldn't I use this for DEcrypting docs encrypted with my
public key? But I digress).

I am also able to add extra UIDs to my public key, so I can have, say 4
different email addresses, all attached to the same public key. Does this
mean I have several SIGNING keys, or several DEcryption keys? How do other
people use my extra UIDs? Can they pick one to use for encryption, and I
must use the "twin" (private) key matching that UID to decrypt it?

Why would I want to create new 'subkeys?' Of what benefit to have, say 5
subkeys belonging to one (master)(private)(signing) key?

What do the letters to the right of the words "usage" mean? (S,C,A,E) I can
only guess |S|ign, |E|ncrypt, ....
##############################################################
felipe at cheetah:/tmp/gpg-kWzpHj> gpg --edit boyd
gpg (GnuPG) 2.0.9; Copyright (C) 2008 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.


pub  1024D/48C1382F  created: 2000-08-19  expires: never       usage: SCA
                     trust: unknown       validity: unknown
sub  1024g/02B5A402  created: 2000-08-19  expires: never       usage: E
[ unknown] (1). Colin Boyd <c.boyd at xx.xx.xx>

Command>

##############################################################

Sorry if this sounds elementary/trivial. I am new to PKI, and encryption,
etc.

I have read through GNUPG gettingstarted manual, and been reading this list
for nearly 1 week. If I have more questions, I hope you don't mind I ask
them here.

Thank you


Felipe
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