在计算机技术中（特别是数据传输和数据存储），块是一段标准长度（块大小）的字节或比特。在处理计算机进程产生的数据流时，块化数据可以简化处理过程。一般情况下，一次会读取一个完整的块。向9轨磁带、旋转介质如软盘、硬盘、光盘和NAND闪存存储数据时，块化数据几乎是唯一的选择。

大多数文档系统都是基于块设备，即访问规定数据块的硬件抽象层。有时文档系统中的块大小可能是物理块大小的几倍。传统文档系统中，单个块可能只包含单个文档的一部分。但由于文档长度通常不是块大小的整数倍，这样文档的最后一块不会完全填满，由此产生的内部碎片会导致空间利用率不高。因此会有松散空间（slack space），平均每个文档半块。一些较新的文档系统会用子块分配和尾部合并技术解决它。

In computing (specifically data transmission and data storage), a block, sometimes called a physical record, is a sequence of bytes or bits, usually containing some whole number of records, having a maximum length, a block size. Data thus structured are said to be blocked. The process of putting data into blocks is called blocking, while deblocking is the process of extracting data from blocks. Blocked data is normally stored in a data buffer and read or written a whole block at a time. Blocking reduces the overhead and speeds up the handling of the data-stream. For some devices such as magnetic tape and CKD disk devices blocking reduces the amount of external storage required for the data. Blocking is almost universally employed when storing data to 9-track magnetic tape, to NAND flash memory, and to rotating media such as floppy disks, hard disks, and optical discs.