Advantages and disadvantages of mobiles, the Internet and social networks

Social networks, mobiles and the Internet are different things, but with all them we can be communicated with other people all around the world, fast and cheap, which is a very big advantage.
But, are everything advantages? The answer is 'no'. Sometimes they can be dangerous. If you don't know the use of a social network, it can be open for everyone. The Internet has so many games that people can become addicted to it. Also, many teens spent a lot of money and time on chatting with their mobiles.
Although, if you know how to use the Internet, mobile and social networks, it will be nice: you will obtain information very quickly, chat with friends, etc.