customary

Notice the root word in “customary” is “custom”, so the two words are very similar. Something customary is done according to practice. For example,

Every culture has its own customary traditions. In American culture, it's customary for a child who loses a tooth to put it under her pillow and wait for the Tooth Fairy to arrive. In Greece, on the other hand, it's customary to throw a child's lost tooth onto the roof for good luck.

Customary can also reference habitual things a person does, like taking your shoes off when you come home or writing in your diary before bed. Used in a sentence, “In America, it is customary for the bride to wear something blue on her wedding day.”