In project management, resources are required to carry out the project tasks. These can be people, equipment, facilities, funding, or anything else capable of definition (usually other than labour) required for the completion of a project activity. The lack of a resource will therefore be a constraint on the completion of the project activity. Resources may be storable or non storable. Storable resources remain available unless depleted by usage, and may be replenished by project tasks which produce them. Non-storable resources must be renewed for each time period, even if not used in previous time periods.