Draining off fats that are released from frying meat or pouring off roasting fats into a bowl gives a slightly burned, dirty fat, full of all sorts from the cooking process - this is "dripping".
Dripping provides the unique flavour behind proper Fish & Chips, and you will still find fryers in the north of England, particularly Yorkshire who steadfastly refuse to move over to oils and trans-fats. Another use, particularly for surplus or a simple thrifty filler for poor families, is what is known as a "mucky fat sandwich" in Yorkshire - simply spread dripping onto bread. Done!
You can tell, we do like our dripping ...
But what about when you've got a glut of fat?
I cooked some belly pork and only wanted the meat, which left a half cup or so of fat once the skin was scraped. The skin made some Pork Scratchings, while the meat went into a kind of Puerco Pibil.
The fat, I rendered ...
If you don't have any fat surplus to requirement by consequence of what you are cooking, just ask your butcher for some fat - it will almost certainly be free.
I know ... I know ... the horror! Non-stick pans and a silicone spatula! I can't use cast iron on my ceramic hob, but we are in the process of moving and there, I will be able to.
Anyway, "needs must", so today I use these pans.
Simply dice and drop into a frying pan on a medium heat.
Clear liquid fat will render out, so periodically pour that off through a sieve into a ramekin.
Repeat a number of times, even pressing down the fat to fully release any final juices.
You will be left with a clear, slightly off white liquid which will cool to a solid, but soft texture.