For example, if I go to some random product page on Amazon, the link looks something like this:
https://www.amazon.com/Really-Long-Product-Name/dp/PRODUCTID/?_encoding=UTF8&pd_rd_w=garbage&pf_rd_p=long-garbage-value-that-doesnt-matter-to-the-user&pf_rd_r=MORELONGGARBAGE&pd_rd_r=another-really-long-garbage-value&pd_rd_wg=garbage&ref_=even_more_garbage&th=1
That link looks ridiculous and isn't suited for sharing in many situations. For most people, this is the link they really want: https://www.amazon.com/dp/PRODUCTID/
I know there are tools out there that can shorten URLs like that. I used to have a browser extension which did exactly that. It doesn't work for everything, but at least your link wont die because a third-party service shut down or messed up.