Very few product or service categories enjoy a homogenous market — one where almost everyone can be served with a single market approach (product, promotion, channels, price).
Instead, it is critical for companies to properly segment the market, select which segments they will target, and develop appropriate market approaches for each segment.
Failing to do so will result in a market approach that is very expensive (trying to reach and serve everyone) but that actually meets the needs of very few.
This article covers market segmentation, targeting strategies, and market sizing.