A postponement of 401K refers to the fact that the money you invest in your retirement plan is taken from your income before taxes, which means they are deferring payment of taxes on that money until you withdraw in retirement.
This does not mean you never have to pay taxes on this income, it just means that you are procrastinating. You must pay taxes when you withdraw retirement money. If this is new to you, you are wondering why would do this. The truth is that no one could, so you want to see the benefits and alternatives and see what works best for you.
401k deferral postpones the payment of taxes on the money invested until you retire. The money invested out of their pretax income, which means decreasing the amount of income that currently has this year. If you hover over a tax bracket, then invest this money can lower your taxes, which means you pay a lower percentage of taxes this year. Besides, if you have a lower income in retirement is now then you will pay a lower percentage in retirement too. This means you save money.
The other advantage is that the money you would have to pay taxes now, however, your account is invested, and growing! This means that the money you would have to pay taxes will make you money in the coming years until retirement, which means more money for you in retirement than they would otherwise. This will help you grow your savings.
Of course, some of these benefits are not applicable to your situation. For example, if your income is lower now than in retirement is that you pay a higher rate of tax on this money. We can make general assumptions about future situations, but for many people is hard to be sure.
You always have the option to take advantage of this option, and another, the dissemination of their tax obligations. Roth IRA using after-tax money, which means they do not have the 401k deferral of taxes. Before making any such decisions, however, it is best to consult a financial professional and become very educated about their options.