What's the Meaning of IBU the Beer Connoisseur⁠↗

Isohumulone is the acid found in hops that gives beer its bitter bite.  Though the IBU scale can be used as a general guideline for taste, with lower IBUs corresponding to less bitterness and vice versa, it’s important to note that malt and other flavors can mask the taste of bitterness in beer. Therefore, a beer with 20 IBUs and a minimal malt character may have significantly more bitter taste than a beer with 60 IBUs and a powerful malt profile.