A memory card is a type of storage device that is used for storing media and data files. It provides a permanent and non-volatile medium to store data and files from the attached device. Memory cards are commonly used in small, portable devices, such as cameras and phones.
Here is an article how the small tiny memory chip stores data files..
Understanding how memory card works requires an understanding of how regular RAM works. One bit of RAM contains a transistor that has a gate that can get switched on. When the gate is on, power can flow through the transistor, and it’s effectively storing a one. However, when you turn the power off to the chip, the gate closes. When you turn the chip back on, the gate doesn’t remember whether it was opened or closed to begin with. This is why RAM gets cleared out when you turn your computer off.
memory cards are also made up of arrays of transistors, but with one difference. In a memory chip, the transistors have two gates — a floating gate and a control gate.When you turn the power on, power flows through the gates and into the transistor, just like in a regular RAM chip. When the power gets turned off, though, some of the power gets stuck in the floating gate and stays there. This is how it stores a value even if it’s turned off. You can read it by sending the power or erase it by sending a negative current that effectively sucks the power out of the transistor.
Flash memory cards, which are really just small. come in different physical sizes and connector types, depending on the style of card they are designed to be. Solid state drives, which replace computer hard drives with flash memory, are typically small boxes that contain an array of flash chips in addition to a Super ATA connector that lets you use them as an internal hard drive and connect them directly to your computer’s motherboard or drive controller.