Second, a likely condition is that there is a natural reason for the neighbourhood to have boundaries that make sense, porous though they may be. This could be built environment features, such as a street or change of housing type, or natural features such as a river or park.
This could also be demographic or ethnographic realities: many of the great urban neighbourhoods over the centuries have been created by concentrations of immigrants from one country gathered together.
Third, a neighbourhood has a scale that is “human” – that is, able to be walked around with relative ease. Again, this is a very vague concept – there have been attempts to develop 15 or 20 minute approaches.
When placed together, these conditions mean that neighbourhoods are a combination of a place where people live and/or work and where they have a feeling of belonging or identification with the people in that neighbourhood. It is possible that they may overlap with other neighbourhoods, or have sub-groups within.