What is Oxoacid?

An oxoacid is an acid in which the acidic hydrogen atoms are bound to oxygen atoms that are bound to a central atom: $\ce{B(OH)3}$, $\ce{H2CO3}$, $\ce{HNO3}$ ($\ce{HO-NO2}$), $\ce{H3PO4}$ ($\ce{(HO)3PO}$), $\ce{H2SO4}$. The more oxygen atoms without hydrogen around the central atom, the stronger the acid.