Cache proxy: This is a way of speeding up Web pages accesses. Normally, when you download a web page, it gets it directly from the web server. This could be on the other side of the world. Using a web proxy with a cache means that your pages are collected on your behalf via the proxy. Common pages will have been already downloaded by the cache, so can be sent to you quicker, provided the cache is nearer to you than the web site itself. For more information see the Cache Now! campaign.

Filter: A filter is a pattern used by WebMask to decide which images and web pages not to load in. These will usually be set to match adverts. The pattern is matched against the URL of the image.

Internet address: This is how computers locate each other on the internet. People refer to these via the Domain Name, such as Computers use a thing called the Domain Name Server to convert this into a number (or IP address), such as .

IP address: See Internet address.

Port: Each internet address has multiple ports which it can connect to the internet through. These are numbered and there are standard numbers to use for web access (80), for e-mail (25), for news (119) etc. By default WebMask uses port 8080 for the browser to connect to it - ports can be used for two programs on the same machine to talk to each other.

Proxy: A proxy is something that you instruct to get web pages on your behalf. In the case of a cache proxy, this speeds up web downloads. In the case of using WebMask as a (local) proxy, this removes adverts from the pages.

RFC: Effectively the standards documents for the internet. To find out technical details about many of the terms in this glossary, look up the following RFCs. You will find them at

Tunnel: This is similar to a proxy, except a tunnel does nothing to the requests, just passes them straight on. It is used to pass on things like secured transactions, which need to be untouched.