AFAIK - "as far as I know"

bandwidth - the amount or rate of data exchanged with news servers

BTW: - "by the way"

catch - the percentage of posts actually received

closed servers - those that are accessed by subscription only

crackers - people with malicious intent who attempt to go where they are
       not "supposed" to, and those who attempt to defeat safeguards

crack - a program that disables the protection features of another program
       or the instructions required to do so

deleters - people who delete other people's posts

ECP - excessive cross-posting - cross-posting to an excessive number of
       newsgroups, often off-topic in some, often commercial in nature.
       Sometimes mistakenly called SPAM.

EMP - excessive multiple posting - posting essentially the same content to
       the same newsgroup(s) multiple times, usually by accident or in a
       misinformed attempt to "make sure that the post gets through".
       Sometimes mistakenly called SPAM.

FAQ - frequently asked questions

flame - a derogatory post made as a follow-up to a post that has offended
       the flamer

flame bait - a post that almost asks to be flamed

flooding - posting large binary files in a large number of small posts

FWIW: - "for what it's worth"

hackers - people with innocent intent who attempt to go where they are
       not "supposed" to, and those who attempt to defeat safeguards

hierarchy - newsgroups of a common prefix such as "alt" or "alt.binaries"

HTH - "hope that helps"

IM[H]O - "in my [ humble ] opinion"

ISP - information service provider - a somewhat ambiguous term that includes
       the service that your modem connects to, the NNTP servers, and several
       other servers

latency - the period of retention before articles are expired

message thread - a series of posts where each is a follow-up to an earlier
       post

newsfeed - the server that accumulates posts from uplink news servers and
       newsfeeds, and distributes them to downlink servers and feeds.

NNTP - Network News Transport Protocol - Usenet news

open servers - those that allow anyone to use them

OTOH - on the other hand

ROTF  - rolling on the floor [ laughing [ my a** off ]]
ROTFL
RORFLMAO

RTMF - read the f***ing manual

spam - posting to multiple newsgroups, usually off-topic and commercial.
       Some mistakenly call anything they object to "spam".

TIA - thanks in advance

trojan - a program that pretends to be a desired program, but when run, does
       something undesirable

troll - a post, usually provocative or controversial in nature, intended to
       evoke a lot of responses.  May be something of a "post a followup with
       your email address" or "all homosexuals should be shot" nature.

Usenet - the network of servers that distributes news posts

virus - a modification made to computer programs that causes something
       undesirable to happen.  An "infected" program will infect other
       programs, the boot sector, or other areas of the hard drive or PC.
       Most viruses lay dormant for a period to mask their origin, while
       they proceed to infect other areas of the PC.  Documented virus
       attacks range from increasing the sizes of files and displaying
       irritating banners to reformatting the hard drives, rewriting the
       BIOS CMOS RAM, and destroying the PC monitor.

warez - actually the "alt.binaries.warez" hierarchy.  These newsgroups are
       dedicated to the propagation of copyrighted or licensed software in
       violation of the copyright or license.
WTF - (What the F***

More acronyms may be found at
Acronym dictionary
AMPFAQ Acronyms
Glossary of Terms/Acronyms