It might sound obvious, but a network is a set of things that are connected. For example, a rail network is a collection of stations connected by rail lines. A railway network is similar to a social network: Some stations are at the edge of the network and connected to the rest of the network by only one line; other stations are major terminals through which a number of lines connect multiple stations.

Some stations are clustered together, forming smaller local networks. An intercity train may carry you between two major city stations, where you would get a local train to a smaller nearby station or move on to the local public transport network. Some stations take you to completely different networks; for example, London to Paris on the Eurostar bridges the UK rail network and the European rail network. Only one train line connects the entire UK and European rail networks, so that line is very important.

Social networks are similarly interconnected groups of people. Like a rail network, they consist of clusters of people who know each other well and links between those clusters. Just like with railway networks, some people are like major stations, connecting lots of railway lines and less-connected stations. Other people are at the edge of networks, like the smaller stations farther out on one line. Some people are really cut off; some are hyperconnected.

Also, social networks are like rail networks because you can generally travel to any point in that network from any point. Some routes will be more direct, and others will require several changes between different lines. If you want to go somewhere in a city, you can walk into any subway station and connect from station to station to reach any other station on the network.

With social networks, you can generally reach a person anywhere in a network by starting off with any random person in or near that network. This is the basis of Six Degrees of Separation, or the Small World Theory, which describes how most people are no more than six steps away through a network from any other person. For example, who do you know, who knows someone, who knows someone, who knows someone, who knows someone, who knows the Queen of England? (You are connected to the queen by six degrees or less.)

Much of what we do with social networks is intuitive, and some people are naturally extremely good at it, but academics also explain it in detail, using terms like weak ties, strong ties, social capital, bridging, and structural holes.

Understanding how social networks function has two advantages. Just as with any system or technology, understanding the underlying mechanisms of social networks allows you to use them more effectively. Also, this descriptive analysis can explain some of the weirder things happening in our lives, like echo chambers.

My Social Network

This is a map of my LinkedIn network:

There are four colored clusters. Pink is my old university. Orange and green represent a country I lived in (one color being the locals, the other being the expats), and blue is my home city. You can see how I sit in the middle of this, and how I’ve connected people from my home city to where I lived abroad.

But you can also see that other people have lines swirling around them between two color groups. These are often close friends of mine who rapidly met a lot of my other friends. If my closest friend becomes friends with a lot of my friends at home, and then visits me abroad and meets my friends there, he too will start to connect those networks.

The map shows how some people have very few links, some people are clustered closely together, and others are bridging between clusters.

The Importance of Weak Ties

This organic social networking process was described in 1973 by Mark Granovetter in “The Strength of Weak Ties.” (You can find it here, and an easier appraisal here.) He wrote about how social networks are composed of weak ties and strong ties.

A weak tie is an acquaintance; someone you maybe know via someone else or met randomly. You don’t have many friends in common, and your networks don’t overlap much, if at all. Because there is very little duplication in that connection, weak-tie contacts tend to know people and information you don’t know. You may approach life differently, and you may not trust each other much, but you bring each other a lot that you both don’t already have in terms of knowledge and people.

Conversely, strong ties are people you know really well and with whom you probably share a lot of common contacts and knowledge. Because you have a lot in common, it’s likely you share similar ideas and a have similar outlook on life. You get on well and have a strong degree of trust between you, which is valuable.

But strong ties are unlikely to offer each other much value in terms of new contacts, new opportunities, and new ideas. If, for example, you went to school together, then you learned the same lessons from the same people, have similar social networks, share many life experiences. This is good when you need to rely on each other, but not when one of you encounters a gap in your knowledge or contacts that requires novel information.

The closeness of strong ties is nice. It’s comfortable being around people who share common ideas, memories, beliefs, and knowledge. It is likely there will be a lot of trust with your strong ties.

In his experiment, Granovetter showed that most people find jobs through weak ties in their network. He concluded that your strong ties generally share the same information, and receiving information you already know makes it redundant.

This redundancy means that the chances of someone in your strong-tie network knowing something you don’t — like a job offer — is quite unlikely. News travels fast, and if five of your close friends know it, you will know it soon, too, and then hear it again and again.

But weak ties, because they belong to other networks of strong ties, not your own, can bring information, news, ideas, and contacts not already running around your core network. This nonredundant information is more valuable to you, because you are less likely to know it already; new information creates new opportunities.

The person who makes that link between networks is called a “bridging tie.” Granovetter argues that while not all weak ties are bridging ties, bridging ties will almost always be weak ties, because strong ties share too much redundant information. Therefore, weak ties are important, hence “the strength of weak ties.”

If you do not have weak ties, you lack access to new ideas, new opportunities, and people with ideas different from yours. In today’s world, as will be discussed, it is weak, bridging ties that help people avoid getting lost in echo chambers. In a tight, strong-tie network, the same ideas and information churn around unchallenged.

You go to networking events to meet people you don’t know and to develop your weak-tie network. This then gives you greater access to new networks of people, ideas, opportunities, and information.

You don’t (or shouldn’t) go to a networking event to hang out with old friends. Equally, you don’t organize an intimate dinner party to catch up with total strangers. That instinctive use of networks is actually a reflection of the value of weak and strong ties and where they fit appropriately into your social network.

Structural Holes

Sociology professor Ronald Burt explored the idea of structural holes in a social network and bridging those structural holes. (You can read it here.) He observed that in social networks, there are gaps between closely networked clusters of people. These gaps, or structural holes, stop the flow of ideas, or goods, or other things that may be needed by either side of the gap.

Whoever bridges these two networks creates value for both of them. What crosses that bridge may be many things; for example, it might be connecting startups with investors, or a product with a market, or simply bringing new ideas and disrupting the way people think. The person who connects the network is bridging those networks and creating value — the bridging tie referred to by Granovetter. That value is both in the novel ideas the person brokers to others and in allowing that person to create new ideas by combining two sets of novel ideas — that is, innovation.

Burt identified that people who are positioned within a social network close to structural holes or at the edges of a network, where it encounters people and ideas that are not at the network’s core, are more likely to receive nonredundant information and create opportunities for their core network. Burt found that this function in a corporate environment led to people getting promoted, because the ideas they generated combined inputs from multiple, different sources and were consequently better and more novel. In effect, innovation happens at the edges of networks.

Burt suggests that the person bridging these networks is an entrepreneur in the literal meaning of the word — someone who is in between, or a middleman. These people can become gatekeepers and brokers of information, contacts, and other forms of value.

His idea differs slightly from Granovetter’s because it suggests that the position in the network and the distance or closeness to structural holes are where people create value, whereas Granovetter suggests it is the strength and quality of ties that matter most. But both combine into a set of theories that are important in relation to work, innovation, and politics.

While these arguments lead to the conclusion that weak ties are important, because weak ties are bridging ties, it is also the case that information gained across a bridging tie into a network is valuable only if the weak ties are complemented by a strong core in a network. This is because strong ties have trust, can rely on each other, and work together well.

Weak, bridging ties are important for accessing novel information, while strong ties are important for capitalizing on that novel information. A network consisting solely of weak ties isn’t really a network at all, but a disparate mess of vaguely connected people who would find it very hard to react quickly to an opportunity and work together.

So, networks require a healthy balance of strong and weak ties, must have bridging ties, and need to be exposed to structural holes, which, when bridged, bring novel information.

Whether or not a social network has all these features can have a huge impact on society, from entrepreneurship and innovation, through disadvantaged sectors of society, to information echo chambers.

The Brexit referendum, for example, can be described almost entirely using this framework, as can climate change denial and Trump’s Make America Great Again campaign. In effect, echo chambers are strong-tie networks with a lack of weak, bridging ties.

People are cut off from information and ideas, or other people, that challenge their beliefs, and they have those beliefs constantly reinforced by those close to them. This begins to explain how, with Brexit and Trump, the votes became so polarized, to the point that each side of the argument simply cannot understand the other.

A key factor to this effect in social networks is the role of social capital and role sets. These will be explored in the next essay.