A large share of household food waste is thrown out because of a printed date rather than anything wrong with the food. The two common labels mean very different things, and only one of them is about safety.
Use by is a safety date. Best before is not
Use by appears on things that can make you ill — fresh meat, fish, ready meals, some dairy. Do not eat these after the date, even if they look and smell fine, because the bacteria that matter are not ones you can see. Best before is a quality date. After it, food may be less crisp, less bright or less flavourful, and it is still safe. This is the label on most of what gets thrown away needlessly.
What is fine long after best before
Dried pasta, rice, flour, tinned goods, honey, vinegar, sugar, salt and most spices last far beyond their date. Spices lose potency rather than becoming dangerous. Eggs are usually fine a week or two past. Put one in a bowl of water: if it lies flat it is fresh, if it stands upright it is older but usually still usable, if it floats, throw it away.
Use your senses in the right order
Look, then smell, then taste a small amount. Mould, an off or sour smell, a slimy surface or a bulging tin are all stop signs, whatever the date says. The reverse is also true: a date that has passed is not, on its own, evidence of anything on a best-before product.
Freeze before the date, not after
Freezing stops the clock but does not turn the clock back. Anything approaching its use-by date can go in the freezer that day and be fine for months. Bread, cheese, milk, cooked rice, cooked meat, herbs and most leftovers all freeze well. This one habit prevents most date-driven waste.
Treat use by as a rule and best before as an opinion. One of them protects you; the other mostly fills bins.