Question

what is Header in computer

Answer 1

Here is the answer to your question !!!

Header refers to supplemental data placed at the beginning of a block of data being stored or transmitted. In data transmission, the data following the header are sometimes called the payload or body.
In other words, In information technology, a header is, in general, something that goes in front of something else and is usually repeated as a standard part of the units of something else. A header can consist of multiple fields, each containing its own value. 

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Answer 2

it is the supplemental data placed at the starting of a block of data that stored or transmitted.
hope it will help u