Pen Drive is an output storage media. It is used to store all the necessary data like documents, movies, pictures, songs, software etc. on the computer. It is also called "flash drive" because it uses flash memory to store files. It is available in different sizes in the market. Such as: 1GB, 2GB, 4GB, 8GB,16GB, 32GB and 64GB etc.
For example,
look pen drive in below picture.