Addressing

In computing, an address space defines a range of discrete addresses, each of which may correspond to a network host, peripheral device, disk sector, a memory cell or other logical or physical entity.

For software programs to save and retrieve stored data, each unit of data must have an address where it can be individually located or else the program will be unable to find and manipulate the data. The number of address spaces available will depend on the underlying address structure and these will usually be limited by the computer architecture being used.

Address spaces are created by combining enough uniquely identified qualifiers to make an address unambiguous (within a particular address space). For a person's physical address, the address space would be a combination of locations, such as a neighborhood, town, city, or country. Some elements of an address space may be the same– but if any element in the address is different than addresses in said space will reference different entities. An example could be that there are multiple buildings at the same address of "32 Main Street" but in different towns, demonstrating that different towns have different, although similarly arranged, street address spaces.

An address space usually provides (or allows) a partitioning to several regions according to the mathematical structure it has. In the case of total order, as for memory addresses, these are simply chunks. Some nested domains hierarchy appears in the case of directed ordered tree as for the Domain Name System or a directory structure; this is similar to the hierarchical design of postal addresses. In the Internet, for example, the Internet Assigned Numbers Authority (IANA) allocates ranges of IP addresses to various registries in order to enable them to each manage their parts of the global Internet address space.

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