Egg cartons do more than just cushion eggs (protecting them against breakage). They also keep out refrigerator odors which can make their way into the tens of thousands of tiny pores in an egg's shell. Because egg cartons are also date-stamped, the carton also helps track how old/fresh eggs are.
Fresh eggs have a higher proportion of thicker "inner" egg white than thinner "outer" white. The inner white is also cloudier the fresher the egg is.
Eggs that sink in water are fresh – particularly great for poaching. An egg that floats outright should be tossed. (It's okay, however, if the wide end sticks up a little out of the water but most of the egg stays underwater.)
A poached egg is great on toast, but it's equally delicious served on top of a bowl of warm Kowalski's Garlic Marinara Pasta Sauce with a hunk of ciabatta bread. Also try it atop a bowl of fried rice with a little kimchee, gouchujang sauce or both.
Large eggs weigh about 2 oz. each. In recipes that call simply for "eggs," this is the egg to use. Recipes that call for extra-large eggs will specify that in the ingredient list. They weigh about 25% more than large eggs.