Each villager has a birthday every year. They won't tell you when their birthdays are, but you can see what day it is by checking the calendar inside of your farmhouse. The birthdays are documented on the calendar after the villager moves to Echo Village.
Giving a villager a birthday gift will greatly increase your friendship with the birthday person. Ideally, you will want to give the villager their favorite gift, but they will accept any gift offering. You will receive a large amount of bonus Friendship Points by giving a gift on the person's birthday than if you have given the same gift on a normal day. Likewise, giving a disliked gift will greatly decrease the amount of FP you have with that person:
|Normal Days||+800 FP||+500 FP||+300 FP||+50||-300 FP||-500 FP||-800 FP|
|Birthday||+3000 FP||+2000 FP||+1000 FP||+500 FP||-1000 FP||-2000 FP||-3000 FP|
|Birthday (Large crop)||+3000 FP||+2300 FP||+1300 FP||+750 FP||-1300 FP||-2300 FP||-3000 FP|
|Birthday (Giant crop)||+3000 FP||+2600 FP||+1600 FP||+900 FP||-1600 FP||-2600 FP||-3000 FP|
If the gift you're giving is a large or giant-sized crop, then you gain more friendship points. For example, on Fall 20 if you give Hana a normal Turnip (a liked-quality gift) then you'll earn +1000 FP. But if you give her a Large Turnip, then you'll get +1300 FP, or a Giant Turnip will earn +1600 FP.
Just like you can give gifts on villager's birthdays, you can receive birthday gifts from the villagers! If you have at least 20,000 FP with a person, he or she will give you a birthday gift when you talk to the person on your own birth date. You don't have to give the person a gift on their birthday to receive one on your birthday; after all, it is better to give than to receive!
The villager will give you a gift from one of four categories. You'll receive an animal treat, bag of random crop seeds, flower bouquet, or bottle of medicine.
Animal Treats: Treat, Chicken Treat, Cow Treat, or Sheep Treat.
Given to you by Aaron, Hana, Hossan, Hina, Neil, Rod, and Toni
Crop Seeds: Turnip Seeds, Cucumber Seeds, Pumpkin Seeds, etc. This also includes tree seedlings, herb seeds, and flower seeds.
Given to you by Clement, Charles, Dunhill, Emma, Felicity, Niko, Sanjay, Soseki, and Tina
Flower Bouquets: Spring Bouquet, Eastern Bouquet, Sunflower Bouquet, etc.
Given to you by Alice, Allen, Amir, Camellia, Michelle, Olivia, your child if it exists, and Yuri
Medicine: Stay Awake, Stamina Booster XL, Feline Friend, etc.
Given to you by the Harvest Goddess, Iroha, Klaus, Kosaburo, Rebecca, Sandra, and Witch Princess
You do need to have room in your rucksack to receive the gift.
If your birthday falls on a festival day, you can still receive birthday gifts. Just talk to the villagers before the festival starts. You won't receive gifts during the festival.
If You're Married...
The birthday changes a little bit after you're married. You still get the presents if you talk to a villager and the villager has more than 20,000 FP, but you will also have a dinner with your family. If your spouse is at a green heart color or higher, enter your farmhouse between 7:00 pm and 11:00 pm to have a special meal. After that you'll receive the standard birthday gift (see list above) from your spouse.
On your family members' birthday, go into your house after 7:00 pm and you'll be asked if you know why there is a celebration meal prepared. If you select the correct birthday choice, then you'll earn +500 FP with your family members and eat a tasty dinner. But, if you select the wrong choice, then you lose -5000 FP with your spouse and child. You will also earn +5 Anger Points (AP) with your spouse. Oops!