Dumb??? Dept.: host alias listings?

[David Armour]

Hello list!

I don't understand networking or aliases, and my brief googling is 
pulling up
stuff that I don't understand more than I do. I'd really like to know
        a) if I should even concern myself with the host alias 
listings..., and
        b) if so, how do I remove/edit the host alias lists from my 
computer.

My story so far:

The other day, while pfutzing around in System/Administration/Network 
Settings/Hosts....
(I was *just* looking!), I noticed the Aliases column to the right of 
the IP Address column
for 127.0.0.1 seemed blurred, or overwritten, so I clicked on the handy 
Properties button...

[upmusic: theme from Jaws]

What I could see was a comparatively long-ish list of aliases that I 
don't particularly
recognize, e.g.:
...
d.abnad.net
e.abnad.net
m3.abnad.net
t.abnad.net
adv.abv.bg
bimg.abv.bg
gtcc1.acecounter.com
gtp1.acecounter.com
acestats.com
www.acestats.com
http.acid-burn.info
ads.active.com
www.activesearch.com
at.ad2click.nl
cms.ad2click.nl
...

...as well as any number of aliases I would actively *prefer* to NOT 
have associated
in any way with my computer, merely by virtue of their names, e.g.:

...
counter12.sextracker.com
counter13.sextracker.com
counter14.sextracker.com
counter15.sextracker.com
counter16.sextracker.com
clit.sextracker.com
clit1.sextracker.com
clit2.sextracker.com
clit3.sextracker.com
clit4.sextracker.com
clit5.sextracker.com
clit6.sextracker.com
clit7.sextracker.com
...

As far as I'm aware, this computer -- a single-user, generic box running 
edgy -- has not
been physically compromised, nor is used to surf such sites.

As always, any responses greatly appreciated.