The Society of Automotive Engineers has established a uniform “connector” standard (J1772) for Level 1 and Level 2 charging, also known as the ‘SAE Combo socket’. Most US-made electric cars currently on the market or due to launch over the next several years comply with this standard (except for Tesla, which uses a proprietary connector – adaptors come with the car to permit connection to any J1772 socket).
European and Asian electric car brands most often use the CHAdeMO socket.
Inexpensive adaptors are readily available to permit inter-operability between the different standards.
DC fast charging (Level 3) connectors are available in several standards and will vary depending on the make and model you choose.