what is unsafe and why?

Mrs P • Wife & mummy to a 10 month old. 👼🏼 11th of Dec 2017 💔👼🏼
My brain is whizzing tonight 😂 another question.
What is unsafe for babies? Cot bumpers are cute but I recently heard why they are so dangerous it's freaked the hell out of me!!!! Just want any information of things that are a no no I wouldn't have known about the bumpers if it wasn't for this app! Any friendly knowledge will help.
Thanks again:)!