Dregs or, perhaps to put it a little bit more politely, using them up. In my humble opinion the best tools for the trade for this are spatulas, teaspoons, scissors etc.
I cut tubes in half and keep the bottom half over the top half to stop the contents drying out. Teaspoons reach the parts of jars not accessible that knives can't [I was going to say corners but jars don't generally have corners I am led to believe] and spatulas are fab for scraping bowls out properly. Bottles are turned upside down or showergels have a little water added to them to get the last bit out. Even tins are swooshed with hot water to make sure that any lurkers are added to the stock pot. My latest wheeze this week has been to use a rolling pin to squeeze the last bit of tomato puree out of the tube.
Maybe this all seems a little too gnat bottomed for some but I don't frankly give a fiddler's flute. I've paid for it and it's all part of my campaign to stop as much of my leftovers unnecessarily going to landfill. I don't reside at Gnat Bottomed Towers for no reason you know!!