Fire typically requires four elements: fuel, oxygen, heat, and a chemical chain reaction. To start a fire there needs to be a source of heat in the presence of oxygen (or an oxidizer of some kind) and a bit of fuel. These must combine to begin the chemical chain reaction needed to generate additional heat, which consumes more fuel and oxygen, generating more heat, and so on. Removing any one or more of these elements will prevent and/or suppress a fire. Creating fire resistant structures then can be as simple as using non-combustible construction materials such as metals, concrete, masonry, clay, sand, glass, cork, ceramics, etc. However, as developed as these materials have become in terms of aesthetics, combustible materials are still typically desirable for interior and exterior design, finish work, furniture, floor coverings, and so on.
An additional prevention step is to exclude oxygen, but for obvious reasons this technique is limited to applying gas impermeable coatings to a limited selection of combustible materials. In doing so care must be taken to avoid generation of poisonous gases and fumes if combustion does manage to start, as they may be more hazardous than the fire itself.
Which leaves the final prevention step of eliminating sources of excess heat, sparks, and exposed flame. Electronic ignition used in gas appliances, spark arrestors, appropriate attention to electrical wiring codes and power usage, and less reliance on flame based heating appliances like fireplaces and wood stoves have significantly reduced the related incidence of fires started by these sources.