There are many useful FTP sites overseas, particularly in North America, but connection can be a problem with these, more so than using e-mail or the World Wide Web. Sending mail messages or reading Web pages does not require a continuous connection between your computer and the remote computer. Mail messages quickly leave your computer and then are routed to their destination via a number of intermediate steps - once you have sent the message you can forget about it as it travels on its way. Similarly, once you have loaded up a Web page and associated graphics in your browser you break the connection with the Web server you got the page from. You only connect to it again if you request a further page, which is a relatively efficient use of the network.
FTP transfers require a continuous connection between the client machine and the server. If the file is a large one then you may need to be connected to the server for some time. If the server is thousands of miles away, this may be a problem: if the network between the two machines gets busier with other traffic, or if the server is dealing with a large number of connections, your file transfer may start to slow down unacceptably. In some cases your connection may even be broken. It is not uncommon to see estimated transfer times of two or three hours or even longer.
One way round this is to provide 'mirror' sites. These are essentially an identical copy of an FTP site at a nearer geographical location. For example, a US site may have mirrors in the UK, continental Europe and Australia. This means that you can connect to the mirror nearby and get the file you are after much more quickly and efficiently. Mirrors are regularly synchronised with the 'parent' site, so they are normally very up to date.
