How many are there
According to the traditional international electrotechnical commission, today in the world 14 standard types of sockets are used. They are indicated in Latin letters from A to N. Each type of outlet can have several different standards.
How do they look
The picture will best answer this question. Most of the connector does not surprise you, although some probably raise the question: “Who invented this at all?”
How about compatibility
Some plugs can be adapted to different sockets. For example, a CEE 7/16 plug can be plugged into sockets of types E, F, H, J, K, L, and even into two-pin type N. And as many sources say, with a certain effort, even in a socket of type D!
But the type L sockets that you may encounter in Italy will make you bewildered and need to look for an adapter. If you are suddenly brought to China or Australia, there, too, you won’t be able to immediately charge your laptop or mobile.
What to do?
If you arrive or come to a country with a non-standard type of outlets, then at the airport (at the station) you will certainly find a counter and adapters of the type you need. If you have time and there is no need to recharge right away right away - you can look for such adapters in the city, for sure they will cost much cheaper there.
Many tourist countries meet their guests and introduce combined standard sockets. For example, in Italy, presa bipasso sockets are widely used - sockets that are suitable for both type C plugs and purely Italian type L sockets. Another country where you can see combined sockets is Thailand. There, in the same connectors you can include plugs of the "European" and "American" types.