I thought the idea of having a password was to allow you in??? What is the point?
The password is to allow
you in. The pictures are to ensure that
you are a human being and not an automated script running on a computer designed to:
a) Steal information (yours, theirs)
b) Consume resources (resources cost money, theirs, ultimately yours)
c) Cause damage (which costs money, theirs, ultimately yours)
Human beings can answer the pictures question - computers cannot (yet). Whether or not you are answering "right" is based on statistical analysis of all the other people who have answered the question, amongst other things (likely the script is also compiling information about your computer to determine if it looks like a real person using a computer rather than a simulated environment, and to try to identify "your computer" across sites by using things like what fonts you have installed, what graphics card you have installed, how the audio driver behaves in your specific machine, what languages you support and a multitude of other data points).