Editing Computer file (section)

==File corruption==
{{further|Data corruption|Data degradation}}

{{multiple image
 | width = 200
 | image1 = Bitrot_in_JPEG_files,_0_bits_flipped.jpg
 | caption1 = Original [[JPEG]] file
 | alt1 = Photo of a child
 | image2 = Bitrot_in_JPEG_files,_1_bit_flipped.jpg
 | caption2 = Corrupted JPEG file, with a single [[bit]] flipped (turned from 0 to 1, or vice versa)
 | al1 = The same photo of a child, but noticeably corrupted: a different color tone and square shapes from the middle to the bottom of the image
 | footer = While there is visible corruption on the second file, one can still make out what the original image might have looked like.
}}

When a file is said to be corrupted, it is because its contents have been saved to the computer in such a way that they cannot be properly read, either by a human or by software. Depending on the extent of the damage, the original file can sometimes be [[Data recovery|recovered]], or at least partially understood.<ref name="techwalla-corruption">{{Cite web |last=Gorski |first=Victoria |title=What Causes a Corrupt File? |url=https://www.techwalla.com/articles/what-causes-a-corrupt-file |access-date=2019-03-17 |archive-date=2020-07-28 |archive-url=https://web.archive.org/web/20200728183934/https://www.techwalla.com/articles/what-causes-a-corrupt-file |url-status=live }}</ref> A file may be created corrupt, or it may be corrupted at a later point through overwriting.

There are many ways by which a file can become corrupted. Most commonly, the issue happens in the process of [[write (system call)|writing]] the file to a [[Disk storage|disk]].<ref name="housonchronicle-corruption">{{Cite news |last=Williams |first=Jane |date=2019-01-14 |title=What Does It Mean When Your File Is Corrupt? |work=[[Houston Chronicle]] |url=https://smallbusiness.chron.com/mean-file-corrupt-70768.html |access-date=2019-03-17 |archive-date=2019-07-15 |archive-url=https://web.archive.org/web/20190715235553/https://smallbusiness.chron.com/mean-file-corrupt-70768.html |url-status=live }}</ref> For example, if an [[Graphics software|image-editing program]] unexpectedly [[Crash (computing)|crashes]] while saving an image, that file may be corrupted because the program could not save its entirety. The program itself might warn the user that there was an error, allowing for another attempt at saving the file.<ref name="howtogeek-corruption">{{Cite web |last=Glenn |first=Walter |date=2017-12-14 |title=What Is a Corrupted File, and Is There a Way to Get It Back? |url=https://www.howtogeek.com/336099/what-is-a-corrupted-file-and-is-there-a-way-to-get-it-back/ |url-status=live |archive-url=https://web.archive.org/web/20181206135510/https://www.howtogeek.com/336099/what-is-a-corrupted-file-and-is-there-a-way-to-get-it-back/ |archive-date=2018-12-06 |access-date=2019-03-17 |publisher=How-To Geek}}</ref> Some other examples of reasons for which files become corrupted include:
* The computer itself [[Shutdown (computing)|shutting down]] unexpectedly (for example, due to a power loss) with open files, or files in the process of being saved;<ref name="techwalla-corruption" /><ref name="housonchronicle-corruption" /><ref name="howtogeek-corruption" />
* A [[download]] being interrupted before it was completed;
* Due to a [[bad sector]] on the [[Hard disk drive|hard drive]];<ref name="techwalla-corruption" /><ref name="housonchronicle-corruption" />
* The user removing a [[flash drive]] (such as a [[USB flash drive|USB stick]]) without properly [[Mount (computing)|unmounting]] (commonly referred to as "safely removing");<ref>{{Cite web |title=What Causes Flash Memory Corruption? |url=https://www.securedatarecovery.com/services/hard-drive-recovery/what-causes-flash-media-corruption |access-date=2019-03-17 |publisher=[[SecureDataRecovery]] |archive-date=2020-07-28 |archive-url=https://web.archive.org/web/20200728192611/https://www.securedatarecovery.com/services/hard-drive-recovery/what-causes-flash-media-corruption |url-status=live }}</ref><ref>{{Cite web |last=Hoffman |first=Chris |date=2016-09-28 |title=Do You Really Need to Safely Remove USB Flash Drives? |url=https://www.howtogeek.com/118546/htg-explains-do-you-really-need-to-safely-remove-usb-sticks/ |access-date=2019-03-17 |publisher=How-To Geek |archive-date=2019-03-30 |archive-url=https://web.archive.org/web/20190330123333/https://www.howtogeek.com/118546/htg-explains-do-you-really-need-to-safely-remove-usb-sticks/ |url-status=live }}</ref><ref>{{Cite web |title=Open a document after a file corruption error |url=https://support.office.com/en-us/article/open-a-document-after-a-file-corruption-error-47df9d48-2165-4411-a699-1786ac734bc3 |access-date=2019-03-17 |publisher=[[Microsoft Office]] Support |archive-date=2019-08-28 |archive-url=https://web.archive.org/web/20190828234354/https://support.office.com/en-us/article/Open-a-document-after-a-file-corruption-error-47df9d48-2165-4411-a699-1786ac734bc3 |url-status=live }}</ref><ref name="datarecovery.net-corruption">{{Cite web |title=What kills your Flash Drive and how you can avoid it |url=https://www.datarecovery.net/newsletters/what-kills-flash-drive.aspx |access-date=2019-03-17 |publisher=DataRecovery.net |archive-date=2018-09-06 |archive-url=https://web.archive.org/web/20180906021351/https://www.datarecovery.net/newsletters/what-kills-flash-drive.aspx |url-status=live }}</ref>
* Malicious software, such as a [[computer virus]];<ref name="techwalla-corruption" /><ref name="housonchronicle-corruption" /><ref>{{Cite web |last=Neagoe |first=Robert |date=2018-08-14 |title=Fix Windows 10 File Corruption Issues |url=https://windowsreport.com/fix-windows-10-file-corruption-issues/ |access-date=2019-03-17 |publisher=Windowsreport.com |archive-date=2020-07-28 |archive-url=https://web.archive.org/web/20200728192245/https://windowsreport.com/fix-windows-10-file-corruption-issues/ |url-status=live }}</ref><ref>{{Cite book |last=International Council of Electronic Commerce Consultants |title=Ethical Hacking and Countermeasures: Linux, Macintosh and Mobile Systems |date=2009-09-24 |publisher=[[Cengage]] |isbn=978-1-4354-8364-4 |pages=2.6–2.7 |language=en |chapter=Mac OS X Hacking |author-link=EC-Council |access-date=2019-03-17 |chapter-url=https://books.google.com/books?id=LYFoU2HG_AkC&pg=SA2-PA6 |archive-date=2020-07-29 |archive-url=https://web.archive.org/web/20200729151154/https://books.google.com/books?id=LYFoU2HG_AkC&pg=SA2-PA6 |url-status=live }}</ref>
* A flash drive becoming too old.<ref name="datarecovery.net-corruption" />

File corruption is typically unintentional; however, it may be done intentionally as an act of [[deception]] so that a student or employee can receive an extension on their deadline. There are services that provide on demand file corruption, which essentially fill a given file with random data so that it cannot be opened or read yet still seems legitimate.<ref>{{Cite web |title=Corrupt a file - Corrupt file online, deliver on time! |url=https://corrupt-a-file.net/ |access-date=2019-03-17 |archive-date=2019-03-23 |archive-url=https://web.archive.org/web/20190323103439/https://corrupt-a-file.net/ |url-status=live }}</ref><ref>{{Cite web |title=Corrupt My File: Get your file corrupted for you |url=https://www.corruptmyfile.com/ |access-date=2019-03-17 |archive-date=2019-03-15 |archive-url=https://web.archive.org/web/20190315142313/https://www.corruptmyfile.com/ |url-status=live }}</ref>

One of the most effective countermeasures for unintentional file corruption is [[Backup|backing up]] important files.<ref>{{Cite web |date=2019-03-07 |title=What is a Corrupted File? |url=https://support.intego.com/hc/en-us/articles/207114508-What-is-a-Corrupted-File- |publisher=[[Intego]] |access-date=2019-03-17 |archive-date=2020-07-28 |archive-url=https://web.archive.org/web/20200728185847/https://support.intego.com/hc/en-us/articles/207114508-What-is-a-Corrupted-File- |url-status=live }}</ref> In the event of an important file becoming corrupted, the user can simply replace it with the backed up version.