Presumably they’re all the tracking crap that FB uses to earn their crust.
Which aren’t necessarily designed for maximum brevity, more for ease of integrating all the dozens of different ad clients of FB who are all eagerly watching to see where on the internet that link appears again and who clicks on it from where.
A link coming from a Google search of the 'net at large isn’t much better.
I just entered a Google image search for [samoyed]. 7 characters of ask. The url of the search results page was 353 characters.
Stripping all the tracking crap out, the minimum link to display the exact same samoyed image search results is 49 characters. The other 300 plus are BS that supports Google’s income but not my ability to see the dog pix.
I clicked one of the first dog pix and the url to show that pic was 416 characters. etc.
Likewise the link that results from a product search on Amazon.
From Amazon’s home page I just searched for [cat food] and clicked the first non-sponsored product on the results page. The url was 139 characters long. Only 37 of them are needed to retrieve the same product page; all the rest is tracking.
(in case anyone wondered, no I don’t have pets. Livestock is for eating, not pampering. That was just the first innocuous topic that popped into my head)
The domain name is merely English for an IP address that is no more than 12 numbers long. I wasn’t even considering it as part of the post com hex.
If the extra 500 characters are tracking code of some sort, then I guess that raises the next level question: if somebody else had generated that link would it be different than my wife’s? Or is much of it simply ignored when a different user posts it?