Something fits in (or on, or with) something else. If the "something else" is known or can be assumed from context we don't need to mention that "something else" or the preposition (in, on, or with) that goes with it. Examples: The shirt fits on me = The shirt fits The toy fits in this box = The toy fits The toys fit in the box = The toys fit

This is a hard question to answer, but I think it depends on the context. In a social context, you say that someone "fits in" with another group of things. It can be a culture, group of people, or something else. Ex. He fits in at his workplace. She doesn't really fit in with our family. That chair fits in with the other decorations in the room. Fit is more general and generally applies to physical spaces. Ex. The puzzle piece fits! The dress fits. (The dress is the right size.) That fits the bill. (Idiom meaning "that makes sense".) "Suit" can be 어울리다 in Korean. Ex. That dress suits you! 이 드레스가 어울려요. They suit each other. (They are good for each other.) "Match" generally has to do with colors/types of things. Ex. That rug matches the painting on the wall. Your eyes match your sweater! Do my skills match the company's needs? Let me know if you have another question!

Ohh! Thank you so much!

This is just my two cents on this: "Fit in" is used when an object or a person is trying to "get in" to something, like a pair of pants or a group of people. Examples: I want to fit in these shoes. I wish I could fit in their awesome group. Are you fitting in your class perfectly? "Fit" has several meanings, but in context on the word "fit in," they're almost similar. They are used differently depending on the structure of the sentence. Here are some examples. Are you fit for this? Do you think you're fit for this job? "Suit" and "match" are two similar words you can use, but it really depends on the sentence/idea you want to convey. "Match" is often used when you are comparing something to it. Examples: You suit the job perfectly. Among all the applicants, you are the perfect match for this job. You are the perfect fit for this job. You are fitting in nicely in your new job. Being happy suits you more. Being happy matches your personality better. Being happy is a good fit for you. Being happy will help you fit in with your classmates. [I am not sure if this helps!]