Obviously we collect the postcode that you enter and the location that you clicked on the map. Without this our work would be a bit of a waste of time.
We also collect your IP address and the time that you submitted the postcode. These are for operational reasons, such as detecting automated submissions.
Finally, like any other website, suring the course of your visit we keep logs of what has been requested from the server.
If you don't want to enter the whole postcode for any location, give us as much as you are happy with. Ideally we would have the whole postcode, but just the first half is still useful to us. More deatils on Postcode formats.
We will be publishing the postcodes and their locations. This is the point of this site, so it is hardly surprising. This will be released into the public domain, so other people may do whatever they like with the data. We will also draw pretty pictures of the data if we get the time.