Retirement savings are mainly built through 401(k) plans and IRAs, with 2025 contribution limits of $23,500 for 401(k)s and $7,000 for IRAs, plus catch-up contributions for those over 50. Employer 401(k) matches should be fully utilized. Investments should be diversified and aligned with risk tolerance, using tools like target-date funds or robo-advisors. Avoid early withdrawals to prevent taxes and penalties. Starting early and consistent contributions maximize compounding growth.