Open, standard protocols are the core of the Internet, some, such as http – the Hypertext Transfer Protocol, are well known, others less well known. Several of these would help smooth the flow of information, make the Internet easier to use, more secure, or enable solutions to be shared more easily if they were more widely known and used.
These are the ones described here.
XMPP – Chat or Instant Messaging
OTP – One Time Passwords
CalDAV – Calendar sharing
CardDav – Address book sharing
PGP – signing or encrypting emails.
LDAP – getting a bit technical, stores data objects
Kerberos – Security