What Is Header?

A header is like the big boss. It's the first thing you see and tells you everything you need to know. When data are transmitted in datagrams, the header holds the essential data such as the source and destination address, packet type and size, and related details. When computers or other devices process documents, they are often split into multiple parts called packets or frames that follow a specific format. These packets contain headers that mark the start of each section of information within them. In addition to these examples, headers can be used for different purposes in different types of documents. The header is the part of a document, data packet or message containing critical information supplementary to the actual data. We know what you're thinking: "A header? Isn't that just something you throw on the fire after eating corn? " Well, not exactly—and here's why. A header has one purpose only: to give you an idea of what's inside the packet or message. It tells you what kind of data it contains and how much there is. It also lets you know where it came from so you can determine whether or not it's trustworthy. The header isn't just for humans, either! Some titles are encrypted, so only specific computers can read them. Others are written in plain text to ensure no one gets confused about who wrote them (or stole them). Any data packet's header is a little like a child's report card. It tells you everything you need to know about the packet—where it came from, where it's going, and what the kid did that made mom and dad so proud (or disappointed). The header is also like the cover letter that college admissions officers read to determine whether or not they'll accept your application. If they don't want what they see in your cover letter, there's no point in reading your resume.