PPTP or Point-to-Point Tunneling Protocol is one of the oldest VPN that it is still in used. PPTP first became available since Windows 95, and it was developed by Microsoft to encapsulate another protocol called PPP (Point-to-Point Protocol). PPTP was widely available in various operating systems even other than Microsoft Windows since around late 90s.
PPTP is one of the fastest, and easiest to set-up. It is also useful for applications the needs fastest speeds such as audio or video streaming, and also on older devices with very limited processors.
However, PPTP is plague with security issues. Its authentication protocol, MS-CHAP-v1/v2, are fundamentally unsecure and it can allow an attacker to exploit cryptographic weaknesses to obtain user credentials as in 2019, Microsoft issued an “Applicability Statement” that the authentication method used by MS-CHAP v2 is susceptible to dictionary attacks. Hence, this protocol is now considered obsolete.
Is this Protocol Available in every VPN providers?
As the PPTP protocol is now considered unsecured and obsolete, most of the VPN providers no longer providing this in favor of more modern VPN protocols such as IKEv2, OpenVPN, etc. Also, Apple already dropped PPTP support in most of their modern devices.