This article discusses the role of histone deacetylase inhibitors (HDACis) in cancer treatment, focusing on their development and mechanisms of action. HDACs are enzymes that remove acetyl groups from histones, affecting gene expression. Aberrant HDAC activity is linked to cancer development, and HDACis are being explored as anticancer agents. The article outlines the classification of HDACs into three main classes (I, II, and IV) and highlights the importance of HDACs in both tumor suppression and oncogenesis. It also describes how HDACis can induce apoptosis, cell cycle arrest, and other antitumor effects. The article reviews current HDACis like vorinostat and romidepsin, which are FDA-approved for certain cancers, and discusses emerging HDACis with improved specificity and efficacy. The challenges in developing HDACis, including off-target effects and the need for better biomarkers, are also addressed. The potential of HDACis in combination therapies and their role in targeting specific HDAC isoforms are emphasized, highlighting the ongoing research to optimize their therapeutic use in cancer treatment.This article discusses the role of histone deacetylase inhibitors (HDACis) in cancer treatment, focusing on their development and mechanisms of action. HDACs are enzymes that remove acetyl groups from histones, affecting gene expression. Aberrant HDAC activity is linked to cancer development, and HDACis are being explored as anticancer agents. The article outlines the classification of HDACs into three main classes (I, II, and IV) and highlights the importance of HDACs in both tumor suppression and oncogenesis. It also describes how HDACis can induce apoptosis, cell cycle arrest, and other antitumor effects. The article reviews current HDACis like vorinostat and romidepsin, which are FDA-approved for certain cancers, and discusses emerging HDACis with improved specificity and efficacy. The challenges in developing HDACis, including off-target effects and the need for better biomarkers, are also addressed. The potential of HDACis in combination therapies and their role in targeting specific HDAC isoforms are emphasized, highlighting the ongoing research to optimize their therapeutic use in cancer treatment.