File Formats ❥ avpres-training ❥ ashley blewer

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# .center[💻 File Formats 💻]

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# ToC

- What is a file?
- What is a file format?
- Magic numbers
- File structures
- Standardization
- Registries

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# Files

Things that can be
- Open
- Read 
- Changed
- Closed
- Permissions modified

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# File Formats

We have many different types of files! These are categorized into different formats, with different ways to determine what to do with the data inside the file.

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# Magic numbers

What separates a file from the rest of the binary landscape?
### Magic numbers!
Magic numbers are sometimes known as file signatures. They are a short string of hexadecimal code that  allow a file to identify itself as a certain type of file.

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# File structure

- Magic numbers (file signature)
- Header
- Body (or payload)

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# File standardization

- Outlines all the rules required to follow to have a valid file
- Can be standardized through a standards body (but not required)
- Can be open (anyone can read) or closed (proprietary, only people in a company/organization can access)

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# Standardization example

A great resource for explaining how a file format is made, by Ross Spencer:
[http://exponentialdecay.co.uk/blog/genesis-of-a-file-format/](http://exponentialdecay.co.uk/blog/genesis-of-a-file-format/)

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# Learning about file formats

- [ArchiveTeam's File Format Wiki](http://fileformats.archiveteam.org)

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# Registries

- [PRONOM](http://www.nationalarchives.gov.uk/PRONOM/Default.aspx) (UK National Archives)
- [Format Descriptions](https://www.loc.gov/preservation/digital/formats/fdd/browse_list.shtml) (US Library of Congress)
- [`file`](https://en.wikipedia.org/wiki/File_(command)) (Unix command)
- [File Formats Wiki](http://fileformats.archiveteam.org/wiki/Main_Page) (ArchiveTeam)

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# Additional Resources

- [Closer Look at PRONOM Signatures](http://openpreservation.org/blog/2010/10/27/closer-look-pronom-signatures/)

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# Learning more

- [Computers](/presentations/computers.html)  
- [Digital Forensics](/presentations/digital-forensics.html)  
- [File Systems](/presentations/file-systems.html)

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