Milonga is a folk guitar music form which was originated in Uruguay and Argentina, based on rhythms brought to the Rio de la Plata by African citizens. In its origins, milonga music would often be improvised, or some milonga songs would be used as a base for improvisation.
Milonga is one of the main bases of tango music. Tango music and dance was born taking much of the milonga as a base. Therefore, tango and milonga are strongly related to each other, and both of them are an important part of the culture of Uruguay and Argentina.
Milonga dance is based on similar movements than tango, but it is danced faster and with more relaxed movements. Also, the dance might vary depending on the milonga and its style, since it can be milonga con traspie or milonga lisa.