Just short

*Disposable income - income after taxes
*Real disposable income - income after taxes on income have been deducted
*normal goods - goods for which an increase in income leads to an increase in demand
*inferior goods - goods for which an increase in income leads to a fall in demand
*substitutes - competing goods
*complements - goods for which there is joint demand
*private costs - the costs incurred by those taking a particular action
*private benefits - the benefits directly accruing to those taking a particular action
*external costs - the costs that are the consequence of externalities to third parties
*external benefits - the benefits that accrue as a consequence of externalities to third parties.
*social costs - the total costs of a particular action
*social benefits the total benefits of a particular action
*non-excludability - situation existing where individual consumers cannot be excluded from consumtion
*free rider - someone who directly benefits from the consumption of a public good but who does not contribute towards it's provision
*non-rivalry - situation existing where consumption by one person does not affect the consumption of all others.
*quasi-public goods - goods having some but not all of the characteristic of a public good.