HDD means Hard Disk Drive.
It is a storage device used in computers, laptops, game consoles, CCTV recorders, etc.
What does 1TB mean?
1TB (One Terabyte) is the storage capacity.
It is equal to:
1,000 GB (Gigabytes)
Very large space for files, videos, apps, games, etc.
What can 1TB HDD store?
Approximately:
250,000 photos
500 hours of HD video
200+ movies
Millions of documents and songs
(These are estimates but give you an idea.)
How HDD works
It uses spinning disks and a moving read/write head to store data.
Because of moving parts, it is slower and can be damaged by heavy shock/drops.
It is cheaper and gives more storage for less cost.