在计算机科学中，随机访问（有时亦称直接访问）代表同一时间访问一组串行中的一个随意组件。反之则称顺序访问，即是需要更多时间去访问一个远程组件。介分两者的传统图解就似比较一轴古代画卷（循序︰所有在组件之前的物料必须事先卷开）及一本图书（随机︰可以随时翻至任何一页）。而更近现代的例子就如比较卡式磁带（循序︰我们必须快速跳过早前的歌曲才可聆听后期的歌曲）及一张CD（随机︰我们可以随意跳至我们想要之处）。不过，RAM一词却被用以作为电脑中的半导体芯片内存电路。

于数据结构中，随机访问暗指可由一堆数字之中，能够持续访问N值的能力，而且除了数组（及相关结构，例如动态数组）以外，绝少数据结构能够作出类似进程。另外，随机访问对不少算法，如快速排序及二元搜索而言不可或缺。其他数据结构，如合并排序，则凭随机访问作出有效率的输入、删除抑或搜索功能。

In computer science, random access (more precisely and more generally called direct access) is the ability to access an item of data at any given coordinates in a population of addressable elements. As a rule, the assumption is that each element can be accessed roughly as easily and efficiently as any other, no matter how many elements may be in the set, nor how many coordinates may be available for addressing the data. For example, data might be stored notionally in a single sequence like a row, in two dimensions like rows and columns on a surface, or in multiple dimensions. However, given all the coordinates, a program can access each record about as quickly and easily as any other, and in particular, access it in time to be of value to the user. In this sense the choice of data item is arbitrary in the sense that no matter which item is sought, all that is needed to find it, is its address, that is to say, the coordinates at which it is located, such as its row and column (or its track and record number on a magnetic drum). At first the term "random access" was used because the process had to be capable of finding records no matter in which sequence they were required. However, soon the term "direct access" gained favour because one could directly retrieve a record, no matter what its position might be. The operative attribute however is that the device can access any required record immediately on demand. The opposite is sequential access, where a remote element takes longer time to access.