AdminMod, AMXMod, MetaMod are what are called addons for game servers. They add functionality as well as extensive management tools for the server admin. There are many other Server enhancements that depend on these addons as well.
Server add-ons are not supported by Steam Support and must be used at your own risk.
A Server admin in need of assistance should visit the official support websites for these tools:
Server plugin MODs, help and support:
The United Admins forum ( is the support center for many addons, including:

C-D Client v4.23.2
C-D Server v4.21.0
ClanMod v1.82b1
HLGuard v1.60 BETA
HLstats v1.20
phpUA v1.1.0b
StatsMe v2.8.2b1 (Beta)
Titan design
CSBot v0.44b
VeXSecure v1.6
MarineBot v0.81 (Beta)
HradBa v204
QMM v0.2.0 Beta