Things that satisfy our needs are said to have utility and usability. These things are called resources.
For an object to have utility, it must have some value i.e. worth. Some resources have economic value, while others do not. However, with time, some resources become economically valuable like the neem tree.
Time and technology are important factors that can change different things into resources.
Resources are generally classified as natural, human-made and human. Natural resources are resources that are drawn from nature and used without much change. Human-made resources are resources made by man from other resources.
Human resources are the people who, with their knowledge, skill and technology, make the best use of nature to create more resources.