This document provides an introduction to VHDL and behavioral modeling. It discusses how VHDL was developed to address the need for modeling increasingly complex digital circuits. VHDL allows designs to be specified at different levels of abstraction through behavioral, dataflow, and structural descriptions. The document reviews key VHDL concepts like libraries, entities, architectures, and sequential/concurrent statements. Examples are given to demonstrate how basic digital components can be modeled in VHDL including gates, multiplexers, and flip-flops.