A β-D-lactose ligand equipped with an azide-functionalized linker through a short ethyl spacer. The terminal azide can be covalently coupled to alkyne partners via copper-catalyzed azide-alkyne cycloaddition (CuAAC), or to dibenzocyclooctyne (DBCO) and related strained alkynes using copper-free click chemistry, forming stable 1,2,3-triazole linkages. This compound provides a lactose (Galβ1-4Glc) building block for glycoconjugate synthesis and the construction of probes for galactose-recognizing proteins, including galectins and the hepatic asialoglycoprotein receptor. It is a substrate for sialyltransferases and other glycosyltransferases.