File allocation scheme where given a file and a size, blocks for the file are allocated in sequence in the file system. The start location and size of the file are stored.
This allocation method is simple and provides fast sequential and random access. Since the blocks are allocated sequentially, they can be read right after another, and the block for a given offset is easily calculated.
Having to know the size of the file ahead of time does not allow for dynamic resizing. As files are removed and added, external fragmentation will occur. If file sizes are overestimated, internal fragmentation will occur.
Contiguous allocation is ideal for situations where files have a predetermined size that will not change. If file sizes will change, and/or if files will be frequently deleted and added, contiguous allocation can end up being inefficient in maximizing file space usage.