10 Lines on Hard disks

1. Hard disks are flat circular plates meant for storage of data.

2. It is made of aluminum or glass and coated with a magnetic material.  

3. Data is stored on their surfaces in concentric tracks.

4. Hard Disk Drive is a type of secondary memory.

5. It can store large amounts of data and has high storage capacity. 

6. Data can be stored on a hard disk for a long time.

7. It is a hand held device, portable in nature.

8. It provides additional storage space for saving data.

9. SATA, PATA, SCSI and SSD are the types of hard drives.

10. It is a type of non volatile storage, retaining stored data when powered off.