Flash memory is a type of EEPROM chip that stores information in a grid of columns and rows with two transistors at each intersection. It is commonly used for easy and fast storage of information in devices like computers, cameras, and video games. To use a USB flash drive, simply insert it into the computer's USB port, then copy files to it. Formatting prepares the drive to accept files and involves selecting a file system and starting the formatting process. Tools like Safe USB and disabling auto play can help protect flash drives from viruses, while making them read-only provides additional protection.