This lecture overviews Human Action Recognition (HAR) that has many applications in semantic video content description, indexing, retrieval, video surveillance and Human – Computer Interaction (HCI).  It covers the following topics in detail: Human Action Recognition (HAR) definition and data, Single-view HAR, Multiview HAR 3D HAR Neural HAR, GCN-based HAR and several Human Action Recognition applications, e.g., in assisted living, sports analytics and gait analysis.