What it is and where it comes from
An emulsifier helps oil and water stay mixed. The word alone tells you little. In Europe it is followed by a name or an E-number, and that is what you check: lecithin (E322) is from soy, sunflower or egg; E471 to E495 are made from fatty acids, which can be plant or animal.
Where you find it
Bread, cakes, chocolate, ice cream, margarine, sauces, dressings and almost every packaged food.
What to look for on the label
Find the E-number or name after the word "emulsifier" and look it up here. Outside Europe you may see only a number, such as "emulsifier (471)". That is the same as E471.
This is a guide, not a fatwa. Recipes change, so check the label, look for halal certification, and ask your local imam where scholars differ.