If a Korean person has been kind enough to invite you over to their house, you should be kind back. And giving gifts whenever visiting a Korean person’s home is pretty standard Korean cultural etiquette. Here are the ins and outs of gift giving when visiting a Korean person’s home!
Why do I need a gift? Isn’t my friendship enough?
Wow, that’s a really self-centered question… But long story short:
In Korea, people like their privacy, and there’s usually other family members living with each other. So it might not be as common to invite people to homes in Korea as it might be in other parts of the world. So if you’re invited to a Korean person’s home, they are being pretty awesome. And don’t you want to be awesome back? Whether it be for a homemade Korean dinner or watching a 30 minute episode of the Simpsons, bringing a gift shows that you have manners in Korea. Korean people much rather prefer to go to someone’s house with a gift in hand than not. If they’re without gift, many Koreans will feel sorry for making an intrusion on someone else’s home turf. So if you want to be polite the Korean way, bring a gift that basically says “thanks for the invite homie!” or “sorry for intruding… and the smelly feet.”
Of course it’s not something you MUST do. But it’s something we suggest for being polite the Korean way 
What Gifts Should I Bring?
General Gifts – If you were just casually invited to someone’s house, gifts don’t have to be expensive at all and they definitely don’t have to be wrapped. Most of the time you can stop by a supermarket and get any food item and it will be just fine. A bag of chips may not be the most inspiring gift, but even something as simple as ice cream can bring a huge smile. Anything boxed and sharable is also a really good gift (i.e. a 10 pack of juice bottles or some apples). Cakes are also common things to bring and are great for everyone to eat after a monster homemade Korean dinner. If you know your hosts like to partake in alcoholic beverages, a bottle of wine or even whiskey are always good gifts. They also have the added benefit of breaking down awkward language barriers
Tip: The price of your gift should reflect the occasion (i.e. big holidays = box of expensive pears, 30 minute episode of the Simpsons = juice variety box).
Housewarming Parties (집들이 – jipdeuli) – We’ve covered this in a previous post, but if you’re going to someone’s housewarming party (집들이/jipdeuli), the traditional gift to give is toilet paper and laundry detergent. We also have tips for gifts for the Lunar New Year (설날-seollal) or the Harvest Festival (추석-chuseok). See link below.
It’s not mandatory to bring a gift. And it’s not like they’ll hate you forever and ever. But they must really like you if they invite you to their house. So be awesome and bring a present to show them that your mama (and Seoulistic) taught you good manners 
If you want to know what gifts to give for a wedding, major Korean holidays or a baby’s first birthday, see this post:
Korean Culture Says Buy These Gifts!
Interesting… In Chinese culture, gifts are also common, but giving pears is a big no-no (The word for “pear” is a homophone with the word for “leave” in Chinese so if you give a friend pears, you’re essentially telling them to leave).
[...] delicious and you’re super happy and full. But then the mom brings out the cake you brought (read why you should here), and you say: “No thank you. I’m full.” After discussing marriage stuff, your [...]
Can I bring home made drinks? (they are really delicious, it is just vodka mixed with a candy that is a little spicy )
or drawings?
Your comment…this is also true where I live in Tanzania. When you visit someones home its customary to bring something, it can be for the whole family (mostly something your mom can cook for you) or if they are kids in the house, something specially for them, that was the reason why I love guest!