Covalent inhibitors bind to target proteins via covalent bonds, offering sustained inhibition and longer residence times compared to non-covalent inhibitors. They are effective against undruggable proteins and mutated kinases, exemplified by nirmatrelvir in COVID-19 treatment and sotorasib for KRASG12C mutations. Covalent inhibitors like sotorasib and adagrasib have shown promise in treating cancers with KRAS mutations, overcoming resistance and expanding therapeutic options.