Assalam u alaikum There are quite a few different additives placed in products which can be seen in the ingredients. Any ingredient derived from animal such as gelatine, some emulsifiers, and even some flavours should be researched to see where they are derived from
For example, not alla gelatine is from pork. I it says beef gelatine, you still need to call up the company to see where they get their beef from, and then call up that beef company to see if they are certified halal. Keep in mind that alot of 'halal' food products and companies arent actually halal according to shariah, they just have the certificate which could be fake. I know alot of people would care about this and probably wouldnt go into as much detail as they should, but if you do it for the sake of Allah swt, Inshallah you will get rewarded for it.
Keep in mind the number codes that come with an ingredient though and do your research, inshallah Allah will make it easy for you to come across what is halal amen
Also bear in mind that alcohol is used in some products as preservatives, though im not sure what the code is for it