Just as social clubs, local taverns or even city plazas and squares filled the role of being the place to mingle and exchange ideas in times gone by, contemporaneously this role is filled by social networks such as Facebook.
This is also why Facebook is different things to different people. For some it is a source to keep tabs on your friends and family. For others, it is a place to rediscover people form your past. Yet for others, it is a place to seek contacts and clients for your business ventures. Facebook is a venue that allows you to socialize as passively or as actively as you wish.