An electronic device is a handheld tool that works electronically. Some examples are small, lightweight computers such as iPads; iphones and other "smart" phones that can connect to the Internet, and handheld game systems.
Ex: The school required all students to secure their electronic devices in their bags and not take them out during the school day.
Ex: I need all my electronic devices, such as my mobile and laptop, with me at all times, because they help me to do my work while I'm away from the office.
Electronic mail is mail that is sent over the computer. It's also called email. It was developed for sending simple messages but has evolved to where you can change the text, colors, and images, and can attach documents as well.
Ex: Kelly O'Mulligan ought to check her electronic mail more often; she had over 200 unread messages yesterday. I wrote to her last month and she never saw it.
A monitor is a device that displays information on a computer screen. It allows the user to interact with the computer.
Ex: Annette, can you please turn on the monitor so that I can enter the sales data for this month and last month in the computer?
Ex: Jim had to buy a new monitor for his office computer because the old one was not working properly and not displaying things correctly.
Monitor can also be used as a verb meaning to watch something, or as a noun to mean a person who watches something.
Ex: A large American university did a study in which people were asked to monitor the effect of the weather on their emotions; the results were very interesting.
Ex: Laura is a history teacher at the local secondary school, and she also has to serve as the adult monitor in the dinner hall twice a month.