Banks are willing to pay more when they know funds will remain in the account for a certain time, as this allows them to plan resource allocation. This leads to the key principle of the deposit market: returns are paid for relinquishing free access to funds.
Contract terms determine actual results more significantly than the stated rate. Important factors include: frequency of interest accrual and payment method, possibility of replenishment, minimum balance requirements, early termination calculation procedures, and renewal terms upon maturity.
Interest may be paid regularly to a separate account or added to the deposit. The first option provides current income, while the second offers compound interest and larger returns, so offers should be compared using effective rates rather than nominal rates.
It's prudent to match the term to your investment horizon: a long-term deposit at a high rate makes little sense if you need the funds earlier and must terminate early. Separately, you should compare the rate with inflation—results are measured by purchasing power, not absolute gains.