The content_type of http has the following form

Text: Text information used for standardized representation. Text messages can be in multiple character sets and or multiple formats;

Multipart: used to connect multiple parts of the message body to form a message. These parts can be different types of data;

Application: used to transmit application data or binary data;

Message: used to wrap an E-mail message;

Image: used to transmit static image data;

Audio: used to transmit audio or sound data;

Video: Used to transmit dynamic image data, which can be a video data format edited together with audio.

You can specify the resource type.
A single operation can only be counted as one request.

You open the browser developer tools, select network, refresh, and you can see all the requests.

When you open a website, the browser will parse the src attribute and generate a new get request. It is the picture you mentioned.

You can understand it this way, everything is a resource. Intuitively, you can map any URL (including relative URL) that appears to a resource, so a document includes pictures. Don’t these pictures all have the src attribute? This is URL, each resource corresponds to a type, that is, the MIME type. As long as the server is willing to provide it and the client (browser) can parse it, there is no problem

http is a transmission protocol. In theory, it can transmit any data (packaged-packaged). The specific legend is actually determined based on the request and response.
In order to facilitate the client to parse the obtained data, the series content_type is defined (after negotiation, declaration, and everyone’s approval), as mentioned on the first floor. But this is just a declarative method, and you can break through it when developing specific applications. For example, although you declare it as text, the transmitted data may be base64-encoded binary data.

Basically all data types can be converted into binary data streams, so basically they can be transmitted.