How the resources on which these people depend for their survival are obtained and used, by women and men, is largely determined by local contexts and customs. Women's knowledge and needs frequently differ from those of men, but similar patterns exist in different parts of the world. For example, timber extraction for household and community construction is often carried out mostly by men (especially in developing countries) while more complex gender roles are identifiable in the collection of non-timber forest products (NTFPs).