206 Partial Content

The body is only the part of the resource asked for in a Range header. How a download resumes and a video seeks.

Class
2xx Successful. The request was received, understood and accepted.
Registered
Yes, in the IANA HTTP status code registry.
Cacheable by default
Yes. A cache may store it without Cache-Control or Expires saying to.
References
RFC 9110 ยง15.3.7 · MDN

Example response

HTTP/1.1 206 Partial Content
Content-Range: bytes 0-1023/146515
Content-Length: 1024

Every 2xx code

All HTTP status codes, in one table