What is the best way to create a web widget that gets parameters from the site that holds it and use those parameters for a web application on a different URL.

Question

I would like to build a widget that should be embedded easily in any kind of website. The widget needs to get a few parameters from the website that holds it, and the widget will run a web application that located in a different URL using those parameters.

i thought about using an script that have the web application url as the source attribute. the parameters should be transfered in the querystring of the source url.

Questions: 1. Does IFrame supported on every/most website architecture? 2. Are there any other options to reach my goal? 3. Is there a better way to pass parameters to my web application that sits in a different URL?

Thanks