因为 (yīn wéi) means because or due to and introduces the reason for a situation. It typically pairs with 所以 (suǒ yǐ, therefore) in a Chinese-style causal structure: 因为...所以... (because... therefore...). Unlike English, both the cause and effect clauses are usually stated. 因为 can also function as a preposition (因为你的帮助, because of your help). In formal written Mandarin, 由于 (yóu yú) is often preferred.