Avian vocalization has been main topics in studying animal communication. The structure and usage as well as development and function of vocalization vary enormously among species and even among populations, and thus we reviewed the general patterns of song learning and the consequences of song communication in birds at the behavioural level: first, we compared the different learning phenomena between non-songbird and songbird, and we investigated the learning process of songbird both in the field and in the lab, which are needed to fully understand vocal communication. Second, we discussed a recent trend of sexual selection hypothesis explaining the structural and functional diversity of song in songbirds with repertoire and presented how the repertoire is actually used between neighbours based on individual recognition.