curl supports numerous protocols, or put in URL terms: schemes.
Your particular build may not support them all.
DICT Lets you lookup words using online dictionaries.
FILE Read or write local files. curl does not support accessing
file:// URL remotely, but when running on Microsoft
Windows using the native UNC approach will work.
FTP(S) curl supports the File Transfer Protocol with a lot of
tweaks and levers. With or without using TLS.
GOPHER Retrieve files.
HTTP(S)
curl supports HTTP with numerous options and variations.
It can speak HTTP version 0.9, 1.0, 1.1, 2 and 3 depending
on build options and the correct command line options.
IMAP(S)
Using the mail reading protocol, curl can "download"
emails for you. With or without using TLS.
LDAP(S)
curl can do directory lookups for you, with or without
TLS.
MQTT curl supports MQTT version 3. Downloading over MQTT equals
"subscribe" to a topic while uploading/posting equals
"publish" on a topic. MQTT support is experimental and TLS
based MQTT is not supported (yet).
POP3(S)
Downloading from a pop3 server means getting a mail. With
or without using TLS.
RTMP(S)
The Realtime Messaging Protocol is primarily used to
server streaming media and curl can download it.
RTSP curl supports RTSP 1.0 downloads.
SCP curl supports SSH version 2 scp transfers.
SFTP curl supports SFTP (draft 5) done over SSH version 2.
SMB(S) curl supports SMB version 1 for upload and download.
SMTP(S)
Uploading contents to an SMTP server means sending an
email. With or without TLS.
TELNET Telling curl to fetch a telnet URL starts an interactive
session where it sends what it reads on stdin and outputs
what the server sends it.
TFTP curl can do TFTP downloads and uploads.
