Their is a proverb if you want to judge a person judge by his friend, I think Facebook is book through which we can find about related person and their friends list also. In whatsapp we can have list of our contact and in mail we can send and receive messages. Facebook is combination off both we want to be in friends list we can add if not we can delete. We can send messages through comments it or detailed shor messages.
Not only that we can do market, share tips , food recipes. Information. Using this also we can also collect peoples opinion on particular thing. It’s act like tv also. Read news.
Personally I like Facebook it gives entertainment, information, tips. But also need caution while selecting friends, posting personal information.