World-building is a prerequisite for readable fiction, but there is no single world which can be used to cover all eventualities within that fiction. Every one of us lives and works within our own smaller sphere. Daily life in Peru is not daily life in Iceland. Life in central Manchester is very different to life on a farm in rural Lincolnshire. Life for a UK family with a combined annual income of £10,000 is totally different to that of a family whose combined income is £100,000.
Each person lives in his/her own world within a larger accepted world. Worlds within worlds are at the very centre of creating believable characters moving within a believable existence.
As an example, consider Crime fiction. For the sake of putting across my point, let's view a police officer as an archetypal pillar of society. He or she might have a spouse, a mortgage, 2.4 children and a dog, a set of blood relatives, a set of in-laws, a group of friends, and then there are the neighbours. This is only one world this police officer inhabits.
There are also the worlds of work. There is the world within the police force, its hierarchy and expected behaviour, standing orders, interpretation of the law, the stresses of manpower shortages and equipment malfunction, dealing with close colleagues on the same shift, colleagues on adjacent shifts, and those in different departments, both officer and civilian. There is the world outside on the street, which might be broken down into three sub-worlds: that of the law-abiding public, the law-breaking public, and career criminals. This police officer will adopt a slightly different persona when interacting with others, depending on the world inhabited. This chosen persona will modify again depending on the officer’s mood or health at the time. He or she is, after all, only human.
People are heavily influenced by their surroundings and the mores of their society, and their smaller spheres of the society they inhabit. Their larger world has an underlying impact on how they think and act, and this can be carried over when they move worlds. Not everyone wishes, or is allowed, to assimilate, and conflict – the motor of any fiction - can result. Taking the UK as an example, consider Colonialism and the British Raj. Consider immigrants to the UK over the last 50 years. Consider modern asylum seekers. Consider affluent UK citizens purchasing ‘a place in the sun’ but refusing to learn the local language. Consider the knock-on effects to all and caused by all. Taking that set of circumstances consider a similar set in your own part of the world.
Closer to home, consider your neighbour. You and your immediate neighbour might share a joined semi-detached property and a fence down identical-sized gardens, but do you share the same worlds? Give some thought to the worlds you inhabit and list these, then consider your neighbour and see how many of your worlds your neighbour shares. There won’t be many, and it will give an indication of just how little you know of your neighbour.
Building worlds is an intrinsic part of creating believable fiction, and as much thought must go into it as into building characters to make the fiction credible and your reader return for more.