A 401(k) is a retirement savings plan offered by many employers that allows employees to save a portion of their paycheck before taxes are taken out. This means that the money you contribute can grow tax-deferred until you withdraw it in retirement, potentially leading to significant savings over time. Employers may also match a portion of your contributions, which can further boost your retirement savings. Participants can choose how to invest their contributions, typically in a range of options like stocks, bonds, or mutual funds. Withdrawals made before age 59½ may incur penalties, encouraging long-term saving. Overall, a 401(k) is a valuable tool for building financial security for retirement.