The course notes present the basic topics of traffic engineering thus allowing the students of Highway Engineering II,, that takes place in the 6th semester of the School of Civil Engineering to familiarise themselves to its basic terminology and main principles. The main principles presented in the course notes refer (a) to the basics of Traffic Engineering (traffic volume, speed and traffic density) (b) to the necessary design parameters of average annual daily traffic (AADT), hourly traffic flow (HTF), passenger car unit (PCU) and (c) to the traffic capacity, the level of service and the peak hour factor (PHF). Examples and applications are presented to provide for a better understanding of the basic topics.