The book "Aligned Carbon Nanotubes" is aimed at students and researchers who are involved with carbon nanotubes and wish to advance their research and development in various application areas. Carbon nanotubes are considered one of the most promising nanomaterials of the 21st century and have garnered significant interest in both research and industry in recent years. This specialized book provides a comprehensive introduction to the topic of carbon nanotubes, with a particular focus on the alignment of these nanotubes. It discusses the synthesis and the microwave absorption properties of aligned carbon nanotubes, based on extensive studies conducted over a period of more than ten years in the author's research group. The book is intended as a useful handbook for anyone engaged in the research and development of carbon nanotubes or looking to become active in this field in the near future.