computer science

Header (computing)

Header (computing) is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Header (computing) rather than just read about it. In short: In information technology, header is supplemental data placed at the beginning of a block of data being stored or transmitted. In data transmission, the data following the header is sometimes called the payload or body.

Key takeaways

Header (computing) belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Header (computing) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Header (computing) from memory before moving on to harder problems.

Reference excerpt

In information technology, header is supplemental data placed at the beginning of a block of data being stored or transmitted. In data transmission, the data following the header is sometimes called the payload or body. It is vital that header composition follows a clear and unambiguous specification or format, to allow for parsing.

Examples E-mail header: The text (body) is preceded by header lines indicating sender, recipient, subject, sending time stamp, receiving time stamps of all intermediate and the final mail transfer agents, and much more. Similar headers are used in Usenet (NNTP) messages, and HTTP headers. In a data packet sent via the Internet, the data (payload) are preceded by header information such as the sender's and the recipient's IP addresses, the protocol governing the format of the payload and several other formats. The header's format is specified in the Internet Protocol, see IP header. In data packets sent by wireless communication, and in sectors of data stored on magnetic media, typically the header begins with a syncword to allow the receiver to adapt to analog amplitude and speed variations and for frame synchronization. In graphics file formats, the header might give information about an image's size, resolution, number of colors, and the like. In archive file formats, the file header might serve as a fingerprint or signature to identify the specific file format and corresponding software utility. In some programming languages (for example C and C++) the functions are declared in header files.

See also Footer Protocol overhead Trailer (computing), used in computer networking Field (computer science)

References

Worked examples

Example 1 — a first encounter with Header (computing)

Start with the simplest possible case. Write down what Header (computing) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Header (computing) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Header (computing) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Header (computing)

In research: Header (computing) appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Header (computing) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Header (computing) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer data, Data transmission, so understanding it makes those chapters shorter.
In everyday life: Look for Header (computing) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Header (computing) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Header (computing) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Header (computing) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Header (computing) in simple terms?

Why does Header (computing) matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Header (computing)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Header (computing).