Some are! TIPS (https://www.treasurydirect.gov/indiv/products/prod_tips_glance.htm https://www.treasurydirect.gov/indiv/products/prod_tips_glan...) are US gover

Some are! TIPS (https://www.treasurydirect.gov/indiv/products/prod_tips_glance.htm https://www.treasurydirect.gov/indiv/products/prod_tips_glan...) are US government-issued inflation adjusted securities. You can also buy debt with coupons based off of other things (like LIBOR). Generally speaking though, bonds are fixed income securities and are not explicitly inflation adjusted. The price you'd pay to buy a given bond fluctuates in part based on market expectations of future inflation.