It is the HTTP server's job to tell its client the type of content being sent. This is done by the Content-Type
header. The value of the Content-Type
header should be a valid media type (formerly known as the MIME type) registered with the Internet Assigned Numbers Authority (IANA). See the Further reading section of this chapter for a link to the IANA list of media types.
There are a few ways to determine the media type of a file. If you're on a Unix-based system, such as Linux or macOS, then your operating system already provides a utility for this.
Try the following command on Linux or macOS (replace example.txt
with a real filename):
file --mime-type example.txt
The following screenshot shows its usage:
As you can see in the preceding screenshot, the file
utility told us the media type of index.html
is text/html
. It also said the media type of smile.png
is image/png
, and the media type of test.txt
is text/plain
.
Our web server just uses the file's extension to determine the media...