The net robots or bots are software gathering , for instance, info about our site for different net browsers e.g the Google. The most often we are visited by the Bing, Google Yahoo robots although I have noticed a couple of others too.
For example .. if you use the Google and write there the name of our site you are displayed with a list of topics, pictures etc.. that are available on our site including the main page of the forum. That's the info gathered by the Googlebot allowing to show you the list and redirect to the address you click.
All the search engines and other info-mining outfits use "spiders" for web-crawling. A website may use a "robots.txt" page in the TLD's index to give the spiders additional commands such as deny access, direct them to a specific page or limit content.
However, the "robots" don't look anything like they're supposed to...
I wrote a bot once to gather some statistics on this site. The thread is probably around still. I did some analysis on popularity of aircraft on the forum and put it in a word cloud. Was quite interesting.