If you write software for end-users today you need a really wide-ranging knowledge. One thing you need to deal with regularly is the question about where to save your data. It is very common to save data on a computer in the WAN or a LAN to make sure the data is available everywhere. You will need to distinguish different users. Your users will have to authenticate with a username and password combination. This is something we need so often in our daily work so that I want to describe a handy way to do so.