Definitions[edit | edit source]

Data packet[edit | edit source]

A header is

[i]dentifying information transmitted as part of the data packet or as e-mail or newsgroup routing information.[1]

Each data packet contains a header that contains the source and destination IP addresses, as well as control and timing information, required for successful transmission. "The information contained in the header is inspected by the router or switch to determine where and how to send that individual packet. This information can be thought of as a mailing label on a package which contains an individual's name and mailing address as well as a return address."[2]

Digital work[edit | edit source]

A header is a section of a digital work where information, data, codes and permitted uses may be embedded.

Electronic mail[edit | edit source]

A header is

the section of an email message that contains vital information about the message, including origination date, sender, recipient(s), delivery path, subject, and format information. The header is generally left in clear text even when the body of the email message is encrypted.[3]
[t]he portion of a message that contains information used to guide the message to the correct destination. Note: Examples of items that may be in a header are the addresses of the sender and receiver, precedence level, routing instructions, and synchronizing bits.[4]

File management[edit | edit source]

A header is a region at the beginning of each file where bookkeeping information is kept. The file header may contain the date the file was created, the date it was last updated, and the file’s size. The header can be accessed only by the operating system or by specialized computer programs.

General[edit | edit source]

In general, a header is a unit of information that precedes a data object.

Network transmission[edit | edit source]

A header is part of the data packet and contains information about the file or the transmission.

References[edit | edit source]

  1. Investigations Involving the Internet and Computer Networks, at 87.
  2. Centripetal Networks, Inc. v. Cisco Sys., Inc., 2020 WL 5887916, at *5 (E.D. Va. Oct. 5, 2020).
  3. NIST Special Publication 800-45, Glossary, at A-1.
  4. Cybersecurity A Primer for State Utility Regulators, App. B.

See also[edit | edit source]

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