If you run a web site, or indeed any other service that's connected to the internet, it's often useful or interesting to know where someone is connecting from. As a server operator, you generally have access to the IP addresses of incoming visitors via various log files. But if you want to know who's behind an IP address, or where they're based, things can often be difficult.
Pinpointing the geographical location of an IP address, known as Geo IP Location, is a specialist art and there are many companies who will, for a fee, provide you with an automated lookup service. One such company is MaxMind. And in addition to their paid-for services, they also offer a database for free download which contains details of around 3 million IP addresses. So if you fancy turning Internet Detective, or you simply want a large dataset on which to experiment for educational purposes, this is a good way to start.
Point your browser at http://dev.maxmind.com/geoip/geoip2/geolite2/ to download the database, which is currently available as a zipped CSV file. The data comprises 2 main files. One is the list of IP addresses, which also contains a location code. The second file, also in CSV format, converts those location codes into real place names, GPS co-ordinates and more.