What are taxable, tax-deferred, and tax-free accounts?

Taxable accounts (e.g. brokerage) typically tax dividends, interest, and realized gains along the way. Tax-deferred accounts (traditional 401(k)/IRA) usually defer tax until withdrawal. Tax-free / Roth-style accounts are funded with after-tax dollars and generally allow qualified withdrawals tax-free. Each plays a different role in a long-term plan.