# Address space > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Address_space > Markdown URL: https://mediated.wiki/source/Address_space.md > Source: https://en.wikipedia.org/wiki/Address_space > Source revision: 1351319795 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) Computing concept This article needs more citations. Please help improve this article by adding citations to reliable sources in this article. Unsourced material may be challenged and removed. Find sources: "Address space" – news · newspapers · books · scholar · JSTOR (September 2025) (Learn how and when to remove this message) In [computing](/source/Computing), an **address space** defines a range of discrete addresses, each of which may correspond to a [network host](/source/Network_host), a [peripheral device](/source/Peripheral_device), a [disk sector](/source/Disk_sector), a [physical memory](/source/Computer_memory) location, a [virtual memory](/source/Virtual_memory) location, or another logical or physical entity. Address spaces are created by combining enough uniquely identified qualifiers to make an address unambiguous within the 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 a data address space may be the same, but if any element in the address is different, addresses in said space will reference different entities. For example, there could be 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](/source/Street_address) spaces. An address space usually provides (or allows) a partitioning to several regions according to the [mathematical structure](/source/Mathematical_structure) it has. In the case of [total order](/source/Total_order), as for [memory addresses](/source/Memory_address), these are simply [chunks](/source/Interval_(mathematics)). Like the hierarchical design of [postal addresses](/source/Postal_address), some nested domain hierarchies appear as a [directed ordered tree](/source/Arborescence_(graph_theory)), such as with the [Domain Name System](/source/Domain_Name_System) or a [directory structure](/source/Directory_structure). In the [Internet](/source/Internet), the [Internet Assigned Numbers Authority](/source/Internet_Assigned_Numbers_Authority) (IANA) allocates ranges of [IP addresses](/source/IP_address) to various registries so each can manage their parts of the global Internet address space.[1] ## Examples Uses of addresses include, but are not limited to the following: - [Memory addresses](/source/Memory_address) for [main memory](/source/Main_memory), [memory-mapped I/O](/source/Memory-mapped_I%2FO), as well as for [virtual memory](/source/Virtual_memory); - Device addresses on an [expansion bus](/source/Expansion_bus); - [Sector](/source/Disk_sector) addressing for [disk drives](/source/Disk_drive); - Various kinds of network host addresses in [computer networks](/source/Computer_network); - [Uniform resource locators](/source/Uniform_resource_locator) in the Internet. ## Address mapping and translation Illustration of translation from logical block addressing to physical geometry Another common feature of address spaces are [mappings and translations](/source/Map_(mathematics)), often forming numerous layers. This usually means that some higher-level address must be translated to lower-level ones in some way. For example, a [file system](/source/File_system) on a [logical disk](/source/Logical_disk) operates using [linear](/source/One-dimensional_array) sector numbers, which have to be translated to *absolute* [LBA](/source/Logical_block_addressing) sector addresses, in simple cases, via [addition](/source/Addition) of the partition's first sector address. Then, for a disk drive connected via [Parallel ATA](/source/Parallel_ATA), each of them must be converted to *logical* [cylinder-head-sector](/source/Cylinder-head-sector) address due to the interface historical shortcomings. It is converted back to LBA by the [disk controller](/source/Disk_controller), then, finally, to *physical* [cylinder](/source/Cylinder_(disk_drive)), [head](/source/Disk_head) and [sector](/source/Track_(disk_drive)) numbers. The [Domain Name System](/source/Domain_Name_System) maps its names to and from network-specific addresses (usually IP addresses), which in turn may be mapped to [link layer](/source/Link_layer) network addresses via [Address Resolution Protocol](/source/Address_Resolution_Protocol). [Network address translation](/source/Network_address_translation) may also occur on the edge of *different* IP spaces, such as a [local area network](/source/Local_area_network) and the Internet. Virtual address space and physical address space relationship An iconic example of virtual-to-physical address translation is [virtual memory](/source/Virtual_memory), where different [pages](/source/Page_(computer_memory)) of [virtual address space](/source/Virtual_address_space) map either to [page file](/source/Paging) or to main memory [physical address](/source/Physical_address) space. It is possible that several numerically different virtual addresses all refer to one physical address and hence to the same physical byte of [RAM](/source/Random_access_memory). It is also possible that a single virtual address maps to one, one, or [more than one](/source/CPU_cache#Homonym_and_synonym_problems) physical address. ## See also - [Addressability](/source/Addressability) - [Flat memory model](/source/Flat_memory_model) - [Namespace](/source/Namespace) - [Virtualization](/source/Virtualization) ## References 1. **[^](#cite_ref-1)** ["IPv4 Address Space Registry"](https://www.iana.org/assignments/ipv4-address-space/). Internet Assigned Numbers Authority (IANA). [Archived](https://web.archive.org/web/20100430190605/https://www.iana.org/assignments/ipv4-address-space/) from the original on April 30, 2010. Retrieved September 1, 2011. --- Adapted from the Wikipedia article [Address space](https://en.wikipedia.org/wiki/Address_space) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Address_space?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.