As I understand it, a "tracking pixel" is a script that contains code that includes a header that make the response appear to be an image, which is then called using an image tag, like:
...so that the code runs automatically/silently, when the page loads the images, for tracking or other purposes.
If I'm correct so far, then my questions are:
What's the advantage? How is this any different from just
.jsfile, with the same code?
Images are often cached (but also refreshed sometimes) - so won't the code run at somewhat unpredictably/irregularly?