1. A method of testing to tell computers and humans apart, the method comprising: providing, by a processor, a challenge on an interface, the challenge comprising a number of selected characters from a challenge character subset, the challenge character subset comprising characters from the 8-bit ASCII character range that leave a visible impression; providing, by the processor, a response on the interface, the response comprising a plurality of characters from the challenge character subset, the response having a character count that is greater than the number of challenge characters and the response including the characters in the challenge, each character in the response having a font size selected from a range having a predetermined maximum, a predetermined orientation, and an x coordinate and a y coordinate, the challenge and the response together forming an image, the image being provided in response to a user request; receiving, by an input device in communication with the processor, a plurality of user selections of locations in the interface, each user selection being associated with an x coordinate and y coordinate; transmitting, by the processor, the x coordinate and the y coordinate of each selection to a server, wherein the server: compares the x coordinate and the y coordinate of each user selection with x and y coordinates for a subset of the plurality of characters in the response to obtain a distance value for each user selection; sums the distance values for each user selection to obtain a total distance value; and compares the total distance to a predetermined threshold, the server validating the user response when the total distance is less than the predetermined threshold, the validating comprising providing access to web content specified in the user request.