An environmentalist is a person who is concerned with and/or advocates for the protection of the environment. An environmentalist can be considered a supporter of the goals of the environmental movement, "a political and ethical movement that seeks to improve and protect the quality of the natural environment through changes to environmentally harmful human activities". An environmentalist is engaged in or believes in the philosophy of environmentalism or one of the related philosophies. The environmental movement has a number of subcommunities, with different approaches and focuses – each developing distinct movements and identities. Environmentalists are sometimes referred to by critics with informal or derogatory terms such as "greenie" and "tree-hugger", with some members of the public associating the most radical environmentalists with these derogatory terms. Source: Wikipedia (en)