The most important job of a food label is to tell you what it contains and if it has undergone any processing i.e. smoked mackerel or dried apricots. The largest ingredients must be listed first.
Pictures
Must not be misleading. If a photo is on the back of a product then it must be contained in the food. If raspberry yoghurt does not contain real raspberry then it must not have a photo of a raspberry on the front, however there is a loophole and a cartoon of a raspberry is allowed.
Flavour
If the word flavour appears on the packaging, the product does not contain real 'xxx' i.e. Smokey bacon crisps do not contain real Smokey bacon. A cheese and onion pasty must contain real cheese and onion.
Use by
This term is for highly perishable goods. The use by date means a food could pose a real health threat if eaten after the use by date.
Best Before
Just as the name suggests, this date is when the food is best consumed by. There will be no threat to health if eaten after this date.
Fat
Reduced fat does not mean low fat. It means a product has substantially less fat that it's rival. For a food to be considered low fat it must contain less than 0.4g fat per 100g.