To not know what ' use by' means?

[newyeardontcare]

His may sound thick, but if it is 'use by' tomorrow. Can I cook it tomorrow? Or does it have to be actually used before that date? I

You can cook it tomorrow, and probably for several days afterwards if it looks and smells ok.

'Use by' means eat before or on that date. If you eat it after that date you may get sick.

'Best before' means it can be eaten after that date without danger if it looks ok, but it won't taste as good.

It means "use on or before" so it'll be fine tomorrow (and possibly a day or two later at your own risk, depending on what it is...).

What Drink says, with the caveat that food may be spoilt before the use by date if it hasn't been stored properly, and may well be ok afterwards, but the manufacture makes no guarantees. Always use your eyes and nose when using food and bin anything off, whatever the date is on it.

Personally, I use use by dates for what to use first, and will use stuff past a date if it smells and looks and finally tastes ok.

It depends on what it is.
If it is something like a ready prepared salad, eat it before or on the use by.
If it is something that you cook, then it's probably safe a day or two after the use by.
Just because it is within it's use by, or best before date, doesn't automatically mean it is ok - for example, if it's a hot day and your food (e.g. sandwich or cream cake) has been in the car all day, it might be a bit off.
You use your judgement, nose and eyes to decide.

Bagged salads like spinach, watercress or rocket can be cooked a day after their use by. Veg is usually ok for days after the use by.