Photoremovable protecting groups (PPGs) are used to control the release of various chemicals, including bioagents, acids, bases, and ions. These groups are essential in organic synthesis, biochemistry, and biomedicine, enabling precise temporal and spatial control over chemical reactions. The review discusses various PPGs, their mechanisms, and applications in different fields. Key PPGs include arylcarbonylmethyl groups, nitroaryl groups, coumarin-4-ylmethyl groups, and others. The review highlights the importance of factors such as absorption wavelength, quantum yield, and stability in the design of effective PPGs. It also discusses the photochemical properties of these groups, their reactivity, and the mechanisms of their release. The review emphasizes the role of PPGs in controlling the release of bioactive reagents and their applications in fields such as neurobiology, enzyme catalysis, and synthetic organic chemistry. The review also covers the photo-Favorskii rearrangement, a key reaction in the release of carboxylic acids, and the factors influencing its efficiency. The review concludes with a discussion of the importance of PPGs in various applications and the ongoing research in this field.Photoremovable protecting groups (PPGs) are used to control the release of various chemicals, including bioagents, acids, bases, and ions. These groups are essential in organic synthesis, biochemistry, and biomedicine, enabling precise temporal and spatial control over chemical reactions. The review discusses various PPGs, their mechanisms, and applications in different fields. Key PPGs include arylcarbonylmethyl groups, nitroaryl groups, coumarin-4-ylmethyl groups, and others. The review highlights the importance of factors such as absorption wavelength, quantum yield, and stability in the design of effective PPGs. It also discusses the photochemical properties of these groups, their reactivity, and the mechanisms of their release. The review emphasizes the role of PPGs in controlling the release of bioactive reagents and their applications in fields such as neurobiology, enzyme catalysis, and synthetic organic chemistry. The review also covers the photo-Favorskii rearrangement, a key reaction in the release of carboxylic acids, and the factors influencing its efficiency. The review concludes with a discussion of the importance of PPGs in various applications and the ongoing research in this field.