The article reviews the impact of agostic interactions (3-center-2-electron M–H–C bonds) on the structures and reactivity of organotransition metal compounds. It traces the historical development of understanding these interactions, starting from the discovery of transition metal alkyl compounds and their unique properties, such as reversible α-elimination and hydride extraction. The introduction of the term "agostic" to describe these interactions was motivated by the unusual behavior of carbon-hydrogen bonds in the presence of transition metals. The article discusses the structural and spectroscopic evidence for agostic interactions, including the acute angles observed in crystal structures and the low 1JCH values in 1H NMR spectroscopy. It also highlights the distinction between agostic and anagostic interactions, where anagostic interactions are not 3-center-2-electron and are better described as hydrogen bonds. The role of agostic interactions in reaction intermediates and transition states is explored, particularly in the context of olefin polymerization and isomerization reactions. The article concludes by emphasizing the importance of agostic interactions in organometallic chemistry and their potential to influence reaction mechanisms and selectivities.The article reviews the impact of agostic interactions (3-center-2-electron M–H–C bonds) on the structures and reactivity of organotransition metal compounds. It traces the historical development of understanding these interactions, starting from the discovery of transition metal alkyl compounds and their unique properties, such as reversible α-elimination and hydride extraction. The introduction of the term "agostic" to describe these interactions was motivated by the unusual behavior of carbon-hydrogen bonds in the presence of transition metals. The article discusses the structural and spectroscopic evidence for agostic interactions, including the acute angles observed in crystal structures and the low 1JCH values in 1H NMR spectroscopy. It also highlights the distinction between agostic and anagostic interactions, where anagostic interactions are not 3-center-2-electron and are better described as hydrogen bonds. The role of agostic interactions in reaction intermediates and transition states is explored, particularly in the context of olefin polymerization and isomerization reactions. The article concludes by emphasizing the importance of agostic interactions in organometallic chemistry and their potential to influence reaction mechanisms and selectivities.