Can you explain what an HTTP request header is?

The HTTP request header is a part of the HTTP request that contains metadata about the request itself and the client. Headers are transmitted as "key: value" pairs and help the server understand how to process the request.

Examples of headers:

• Content-Type: indicates the type of content sent by the client.
• Authorization: contains authentication data.
• User-Agent: information about the client application.
• Accept: data types that the client is willing to accept in response.

For example, a header:

User-Agent: Mozilla/5.0

indicates to the server that the request was made from the Mozilla browser.

Thus, headers play a key role in communication between the client and server, ensuring proper processing of requests and responses.