A Hard drive is a storage device which allows you to store files into your computer. It writes and retrieves data/information.
Optical Drives use lasers to read discs. It is usually used in DVD players.
A monitor is a visual display for computers.
An input device is an item or command which is inserted into a computer. The command tells the computer what to do and makes it an output device. For example if you type on a keyboard words pop up on the screen.
Touch screens were made by Steve Jobs and the Apple company. It uses touch to let the user control a device. It is mainly used for tablets and smart phones.