"by" 是一个 英语介词和副词，其基本含义包括：
靠近 或 在……旁边
She walked by the river.
There is a book on the table by the window.
通过或 凭借……
They traveled to New York by plane.
She learned English by reading books.
在……之前
Meet me by the entrance.
We need to finish the work by Friday.
表示方式或手段
They arrived by car.
She sings by ear.
表示被动
The cake was baked by her.
I was attacked by a dog.
在网络用语中，"by" 有时也用于表示某些词语的首字母缩写，例如：
BYD（比亚迪）
BYD（包养）
根据上下文的不同，"by" 的具体含义可能会有所变化，但以上列举的是其最常见和核心的用法。