This presentation summarizes various secondary storage devices and their characteristics. It discusses magnetic tapes, magnetic disks, floppy disks, optical disks, memory cards, DVDs, and pen drives. For each device, it describes the structure, advantages, and disadvantages. Magnetic tapes provide high durability but only allow sequential access. Magnetic disks allow random access but are more prone to errors. Floppy disks have limited storage capacity and are difficult to handle. Optical disks have large storage capacity but are non-reusable. Memory cards, DVDs, and pen drives provide portable storage options with increasing capacities over time.