Moved to its own page.
zipcode.php looks up an address using the US Postal Service site to find its address in standard form, including zip code (with the 4 digit extension.) This is for checking it automatically within php without user interaction. If you just want to looks something up yourself, see Their site.
For example, see Google's First Home
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Threads after compacting:

A more complex display
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A Goofy example blog comments style.
I once had to deal with an application that did this on a regular basis.
I once tried looking for wifi in my area.
Someone showed me this picture. After going to the website, I saw this. I like NoScript.