# What are networks?

Watch Dr David Millard explore what we mean by a network, and look at some of the examples of networks around us and their characteristics.

Networks are all around us, but have you considered what makes a network, and what shapes and properties they may have? Understanding networks in an abstract way (as nodes and edges, without worrying about what they actually represent) gives us access to many mathematical techniques for understanding and comparing them.

In this activity we will explore what we mean by a network, and look at some examples of the networks around us. Networks are structures with common properties and characteristics, so we will also explore some of the ways in which we can describe a network, and the different types of network we can identify as a result. In Web Science seeing structures as a network is a very powerful way of understanding how they might behave, but we must also never forget that while they may share properties, those properties arise from very different processes.

Seeing activity on social media as a network allows us to explore how connections form, to identify important network nodes, and compare networks of otherwise dissimilar things.

In this video we cover some of the basics of networks, and see how many real life networks turn out to have a common scale-free structure and an important small-world property.

Once you have watched this video lecture by Dr David Millard you should also watch the accompanying videos (linked to this article):

• The first is an interview with Duncan Watts, whose PhD thesis from Cornell University explored the phenomenon of small-worlds.

• The second is a brief trailer for a TV documentary called ‘Connected: The Power of Six Degrees’. This illustrates the current excitement that there is around Network Science and it gives us hints as to how broadly applicable these ideas are, and what they might mean for our health and wellbeing. Both Laszlo Barabasi and Duncan Watts appear briefly in this.

In the first part of this week we look at the different shapes and properties that networks have. When we have an ability to represent and describe them in this abstract way we can start to analyse them to answer questions about the things that they represent.

Later on in the week we will present an exercise ‘Who is the most powerful person in a social network?’ to analyse the activity of a small office network. We will use the connections and messages they have generated to calculate who the most influential person is.