HTTP responses have:

• a status code (200 OK! 404 not found!)
• headers
• a body (HTML, an image, JSON, etc)

Here’s the HTTP response from examplecat.com/cat.txt:

HTTP/1.1 200 OK
status
Accept-Ranges: bytes
Cache-Control: public, max-age=0
Content-Length: 33
Content-Type: text/plain; charset=UTF-8 Date: Mon, 09 Sep 2019 01:57:35 GMT
Etag: "ac5affa59f554a1440043537ae973790-ssl"
Strict-Transport-Security: max-age=31536000
Age: 0
Server: Netlify
[ASCII image of a cat, labelled "cat!" with a smiley face]

The first line, HTTP/1.1 200 OK is the status code. “200” is the status.

The lines from Accept-Ranges to Server are the headers.

The cat picture is the body.

There are a few kinds of response headers:

• when the resource was sent/modified:

  Date: Mon, 09 Sep 2019 01:57:35 GMT
  Last-Modified: 3 Feb 2017 13:00:00 GMT
  

• about the response body:

  Content-Language: en-US 
  Content-Length: 33
  Content-Type: text/plain; charset=UTF-8
  Content-Encoding: gzip
  

• caching:

  ETag: "ac5affa..."
  Vary: Accept-Encoding
  Age: 255
  Cache-Control: public, max-age=0
  

• security: (see page 25)

  X-Frame-Options: DENY
  X-XSS-Protection: 1
  Strict-Transport-Security: max-age=31536000 
  Content-Security-Policy: default-src https:
  

• and more:

  Connection: keep-alive
  Accept-Ranges: bytes
  Via: nginx
  Set-Cookie: cat-darcy; HttpOnly; expires=27-Feb-2020 13:18:57 GMT;