Asset allocation is an investment strategy that aims to balance risk and reward by apportioning a portfolio's assets according to an individual's goals, risk tolerance, and investment horizon.
The three main asset classes - equities, fixed-income, and cash and equivalents - have different levels of risk and return, so each will behave differently over time.
Your portfolio structure should be spread through all asset classes, different geographies, and sectors. Invested both in the UK and overseas and should not be focused in one area.