how have people communicate with their friends changed in recent years

The public who communicating with their friends have changed significantly over the past few decades. In the past, people keep contact with their friends via letters which a major method of communition. Writing letters is quite time-consuming, for example, it took several days or even weeks for the recipients to receive them. But now, mobile phones are more and more popular, citizens can enable to easily interact with anyone immediately with social media, such as emails, messenger and zalo. The only thing you guarantee that when you use those cell phones to exchange each other, your equipments are definitely connected to the Internet.