在计算机磁盘存储器，一个扇区（英文：sector）是磁盘或光盘上一个磁道的分区。每个扇区存储固定数量用户可访问的数据，传统上512字节对于硬盘驱动器（HDD）和2048字节对于CD-ROM和DVD-ROM。较新的硬盘驱动器使用4096字节（4 KiB）扇区，这被称为Advanced Format（AF）。

In computer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. Each sector stores a fixed amount of user-accessible data, traditionally 512 bytes for hard disk drives (HDDs) and 2048 bytes for CD-ROMs and DVD-ROMs. Newer HDDs use 4096-byte (4 KiB) sectors, which are known as the Advanced Format (AF).