A Botnet is a group of lots of computer systems. They have been hacked in various ways so they are now being used (as zombies computers) to send spam emails or to attack websites. The way such a group of computers was created is with the help of compromised applications called "bots". Those bad programs will turn your PC into zombie one that hackers can control at distance with the help of a "bot-herder" command system and a control server. One of the most dangerous threat menacing the cyberspace are the Botnets. Those groups of zombie computers can do lots of damages to personal PCs, whole networks, and more. In addition to sending spam emails, botnets are used to distribute adware and spyware as well. Denial of Service (DoS) and Distributed Denial of Service (DDos) are 2 others popular methods to hurt servers that hackers are doing with those Botnets. They will try to massively overload a system so it won't work anymore because there are too many requests to acceessit at once. Here Online Virus Removal you can find a great online service ready to repair any problems your PC may have.

The way to get infected is via Trojans and viruses that carry the botnet's threat part of its code. Any of those spam emails you do receive can lead to some trojan or virus ready to infect your PC. If you go to some fake websites telling you to install a fake codec (and not a good video or audio one), it might be a way to infect your PC. After having infected your computer, this threat will connect to its bot-herder server for further instructions. That includes sending more spam emails, trying to infect more computers and starting some kind of attacks on some servers. Most PC users will not even remark that they have a Botnet unto their computer and thus none of the previous activities will be easily detected. So to detect such a threat is very important. This site Virus Removal Guides has good infos about spyware removal.

If you do notice your PC is slowing down, this might be a sign it is infected with a botnet. Another problem is that your internet own connection will be slower than usually. This is because the botnet is connecting itself to lots of places. You might notice 2 more things: you have less hard disk space than before and your browser is not working as usually. If your desktop has been changed or your browser's homepage is not the same one as before or it is closing with no apparent reasons, you might be infected.