This lecture covers the properties and applications of titanium alloys, focusing on Ti as the 4th most common element in the earth's crust, the complex processing route of Ti alloys, their use in aerospace and racing car applications, and their biocompatibility for biomedical implants. It also discusses the crystal structures of Ti, the role of alloying elements, classification of Ti alloys, strengthening mechanisms, microstructures, and textures in Ti alloys.