Tax-loss-harvesting is a tax planning technique in which investors sell their ‘losers’ to lower their taxes. If you realize losses by selling securities or crypto assets, you can offset realized gains and thereby lower your tax liability. If you have no or too little realized gains, you can offset up to $3,000 of ordinary income. If you have more realized losses than realized gains, you can carry forward your realized losses to subsequent years to apply them to subsequent realized gains. Tax-loss-harvesting is not applicable to tax-deferred retirement accounts and you need to consider the wash-sale rule (the offset of losses is not permitted if you repurchase the same or a substantially identical security within 30 days. As the IRS classifies crypto as property, the wash-sale rule currently does not apply to crypto. This is likely to change soon.). https://www.irs.gov/taxtopics/tc409