Biological diversity (\’biodiversity\’) – the variety and variability of life on earth, including genes, ecosystems, and species – is a fundamental measure of the state of nature and its ability to deliver benefits (ecosystem services). Globally, biodiversity is in decline. The UK State of Nature report in 2019 showed a decline of 13% in species abundance, which continues a long-term pattern of significant biodiversity losses and a failure to meet nature recovery targets.\r\n\r\nBiodiversity net gain is an approach to development and land management that aims to leave the natural environment in a measurably better state than it was beforehand. Net gain is an important development for landscape professionals, who collectively have long advocated that proper planning and design are crucial to maximise the benefits that ecosystem services provide. This briefing discusses in more detail why net gain is a key concept in landscape practice; explains what role landscape designers, planners, and  managers can play in delivering net gain; and answers questions professionals might have about its implementation.