About the Floppy Disc and USB
A longt time ago floppydiscs were still used as a storrage medium. The laptops of today dont even have a floppy disk anymore, and so its not possible to read-out the floppys. A disk space of 1.44 MB was the maximum of the floppy. You could format them as required and to store new venues. Next was the CD-ROM.A longt time ago, the working stations had indeed already a standard CD-ROM drive, but it took some time to have the CD writer fitted as standard in standard PC. Until then, there were many computer applications to buy on CDs, but data storage was not possible on them. Quite at the same time then the USB sticks, SD cards and external hard drives came to the market.
The latest storage medium
The Micro SD card has the benefit that it is smaller and is used as a storage medium in digital cameras, for example. As a disk outside of such devices, it is rarely used, because not every PC has a Micro SD card slot. Therefore these digital camera always are supplied with cable to join the device directly to the PC. The external drive has big memory space, the current ones have 1000 GB, or 1 TB in size. However, most need an external own power source, they ar massive and unwieldy. Better as this is the Memory sticks. All working stations have one or more USB slots, the stick needs little power and is easy to carry in your bag. These three storage media are always refined and getting more and more memory space. The current speed of development is such that the capacity every year doubles. Still not in price. A year ago you got an external hard drive with 500 GB for about 100 . Today they are twice as large for the same price.