why are HTML checkboxes sometimes problematic for managing true/false values

Can someone explain,
why are HTML checkboxes sometimes problematic for managing true/false values via form submissions?

thanks in advance?

Sounds like an interview or homework question. What's your answer?

And yes, I have the answer -- but we want to hear what you think first.

Yes it was a interview question .... i couldn't hit it .....

Only thing i know is that checkboxes are used to take multiple inputs from the user in case of a form submission...

Tulip Jain wrote:Only thing i know is that checkboxes are used to take multiple inputs from the user in case of a form submission...

Not always. Like most other controls, you can have multiple values by giving them all the same name, but that's not an attribute of the checkbox itself.

The answer is that when a checkbox is unchecked, it does not take part in the submission at all. A value is submitted only when the checkbox is checked. So rather than checking a param for a value such as true or false, you need to check for the existence of the parameter itself.

Thank you so much ... for clearing the concept ...