In Plato's Allegory of the Cave, a group of people have spent their lives chained in a cave, where they are unable to turn around. All they can do is watch the shadows of reality that firelight cast on the wall in front of them. They can't see the real objects themselves. They mistake the shadows of reality for reality itself, because that is all they know.
In 1966, Peter L. Berger and Thomas Luckmann coined the term "social construction of reality" in their book of the same name. Customs, social institutions, common ideas about the way the world is, and even sayings or proverbs shape our reality.
The social construction of reality also says that our perceptions of the world are shaped by who we are in society and by what is known as our "social location." This means that factors like our economic status, gender, educational level, race, ethnicity, geographic location, and age deeply influence the way we experience the world.
As with the figures chained to a spot in Plato's cave, our social construction of reality also "chains" us, metaphorically speaking, to a certain way of understanding the world. This can be reinforced by the echo chamber of social media if we surround ourselves only with people like us.
In order to build up a truer picture of the world, it is important to try to look at the world as it might be experienced by people in different social locations. In other words, we don't want to look solely at the shadows or representations of reality all around us, but try to see reality itself.