What is an "eSIM"?

The abbreviation "eSIM" means "embedded SIM":

Unlike the normal SIM card, it is permanently installed in the device as a small chip.
It measures 5 x 6 mm and cannot be replaced or removed.
An eSIM uses the same specifications as an ordinary SIM card.
So technically it doesn't matter whether you use an eSIM or the conventional SIM card format.
If you want to switch to a different phone provider, the eSIM is simply reprogrammed.
To do this, for example, with Apple iPhones you simply scan a QR code transmitted by the provider. Alternatively, you can use the provider app or enter the eSIM information manually.

eSIM: Differences to the normal SIM

 
New eSIM
Old SIM
Installation
Is already permanently integrated in the device
Must be plugged in
Change
Cannot be taken out and will be reprogrammed when changing provider
Can be removed and replaced with other SIM
Dual – SIM
Some devices, such as the newer iPhones, offer the option of using an old SIM in addition to the eSIM.
Depending on the device, possible, for example, to use one SIM card as a cheap data tariff and the other SIM card for making calls.

	New eSIM	Old SIM
Installation	Is already permanently integrated in the device	Must be plugged in
Change	Cannot be taken out and will be reprogrammed when changing provider	Can be removed and replaced with other SIM
Dual – SIM	Some devices, such as the newer iPhones, offer the option of using an old SIM in addition to the eSIM.	Depending on the device, possible, for example, to use one SIM card as a cheap data tariff and the other SIM card for making calls.