MicroSD cards were launched around the mid-2000s, intended for use in small devices like mobile phones and cameras.
Their initial capacity was 128MB. Since then, they have greatly evolved both in capacity and reliability.
They continue to be unreliable as devices, as they rely on Flash technology (with all that entails), but they are a very good solution for transferring data from one device to another.
These cards have all their subsystems integrated into one piece. There is no separate chip for data writing, no separate chip for the controller/CPU, etc.; it is all in one medium. Their operation is particularly complex, and their recovery is usually an extremely laborious and time-consuming process.
If you have such a card that has stopped working, take advantage of the MicroSD data recovery service and get in touch with us for the details.