The answer is there are 2 basic models, a traditional IRA/403b and a Roth IRA. Under the first category, money is pulled from your check before it is taxed. Nice, but when you retire it will be taxed. The second kind is a Roth IRA, money is taken out post taxing and hence is non taxable when you retire. What I just said is a simplification and I am not a tax professional.

If it were me at your age, I would go with a Roth. You will pay taxes on a dollar but may get 10-15 back untaxed for that same dollar when you retire.

However, if you go thru your employer...most of us do. You are probably going to have to suck up whatever they are offering.