Amanzi yinto enekhemikhali enefomyulayekhemikhali engu-H2O. Imoletyhuli yamanzi ine-oksijini kunye nee-athom ezimbini ezinxibelelene ngekhonkco elibizwa ngokuba zii-covalant bond. Amanzi alulwelo oluye lube kwiimo zokubanda okanye zobushushu obungaqondo-ngamaqondo, kodwa loo maqondo asoloko ehamba ngokwemeko zomhlaba, enye yezi meko yenza okokuba amanzi aqine abe ligaqa, sithi ke ngoko angumkhenkce. Aphinde kwawona laa manzi anyibilike abe ngumphunga (umphunga wamanzi). Amanzi asoloko eba ngamanzi xa ekufuphi kwiindawo ezinamanzi. Xa amanzi ephantsi kwento ebizwa ngokuba yi-nomenclature adla ngokuba likhonkco leekhemikhali. Ihadrojine monoksayidi ligama lobunzululwazi lamanzi, elingasetyenziswa kakhulu.