The short list

• Pork, and anything derived from it (gelatine, lard, some enzymes).
• Alcohol: drinking it in any quantity. (Vinegar is fine; trace alcohol naturally present in bread or ripe fruit is not the issue; drinks are.)
• Meat not slaughtered Islamically: the animal must be slaughtered with God's name pronounced, swiftly and humanely. Meat of Jews and Christians ("People of the Book") is addressed in the Quran (5:5) and scholars differ on how it applies to modern industrial slaughter; many converts simply look for the halal label to keep life simple.
• Blood, carrion, and predatory animals: mostly theoretical in a supermarket.

Seafood is halal in the mainstream view (all of it, in the Shafi'i, Maliki, and Hanbali schools; the Hanafi school limits it to fish). Everything else in the produce, dairy, grain, and sweet aisles is halal by default unless an ingredient sneaks in.

Reading labels

• Gelatine: assume pork unless marked beef/halal/fish. Hides in sweets, marshmallows, some yoghurts and capsules.
• Alcohol as an ingredient: obvious in beer-battered and wine sauces; also check vanilla extract debates don't consume you; cooked-in alcohol in a dish is avoided, trace carriers in flavourings are broadly excused by many scholars.
• E-numbers: E120 (cochineal) is debated; E441 (gelatine) and E920 (L-cysteine, sometimes animal-derived) are the ones to know. Apps and halal-certification marks do this work for you.
• "Suitable for vegetarians" is a convert's best friend: it rules out both pork and slaughter questions at a stroke.

Real situations

Eating at non-Muslim family's table. Eat the vegetarian and fish things gladly, quietly skip the rest, and don't turn dinner into a tribunal. Kindness to your mother is also a command. Most families adapt fast once you gently explain; many start buying halal chicken for your visits, and that gesture is love: receive it as such.

Restaurants. Seafood and vegetarian restaurants are effortless. Elsewhere: fish and veggie options, ask about alcohol in sauces, and relax; scrupulousness is a virtue, paranoia is a burden Islam never asked you to carry.

The work party. Attending isn't haram; drinking is. A soft drink in hand answers most social pressure before it's voiced. If the event is essentially a drinking session, leaving early is self-respect. Sitting at a table where alcohol is served is an area where scholars urge avoidance when practical; use judgement and don't isolate yourself from every colleague.

Mistakes. Ate something haram unknowingly? Nothing is held against you; the sin needs knowledge and intent. Knowingly slipped? Repent and move on. No food failure removes you from Islam.

Beyond food

Halal describes a whole economy of conduct: honest income (see the money guide), truthful speech, and clean dealings. The Prophet ﷺ warned about the man who prays and fasts yet eats haram wealth; a halal fridge with a haram salary misses the point. Food is just the daily training ground for a bigger idea: living inside the boundaries of the One who set them, and finding them roomy.