A Venn Diagram in Logic is a visual representation of the relationships between two or more sets of data. It is used to illustrate how the elements of one set are related to the elements of another set. The diagram consists of overlapping circles, each representing a set of data, and the area where the circles overlap represents the elements that are common to both sets. Venn diagrams are useful for analyzing and comparing data, as well as for understanding the relationships between different sets of data.