What are File Extensions or suffixes?

File extensions or 'suffixes' are a very crucial part of the computer world. Without file extensions, some operating systems will have problems in recognizing and organizing files.

File extensions/suffixes are markers which inform us and the computer what source application a specific file is associated with. Mostly, these are combinations or abbreviations designed by the developer of the application which created the file.

You may name a file image1 but it needs a file extension/suffix after it for the computer to recognise the application which the file was created in. These are signified with a dot and a number of digits after it

For example: If it is a Photoshop document the suffix would be image1.psd
If it is a InDesign document, these files are associated with the .indd file extension.

Files can only be opened with applications similar to the one that was used to create the file. However, there are some exemptions. Earlier versions of Microsoft Word applications such as those released prior to the 2007 version are provided with the file extension .doc and Microsoft Word 2007 documents are saved with file extensions .docx which is an extended XML format of word documents. Though developed by the same company and with similar standards, earlier versions of Microsoft Word will not be able to open files with extensions .docx unless provided with the compatibility software. However, backwards compatibility is mostly supported by newer software applications.

Here is a link to a site that gives file associations and related file types:

http://www.sharpened.net/extensions/browse/a

Hope I've explained it right and easily for you!