The following types of  resources can be specified for your project schedule: work, material, and cost.

• Work resource - A work resource is anyone or anything that is needed to complete a project such as people and machines. Typically resources are people involved in your project whether or not they are assigned tasks. Equipment can include web servers or computers that have special software needs to accomplish certain tasks. Work resources need time (hours, days, weeks) to finish the task.
• Material resource - A material resource includes things that are consumed by a task such as paper, pens, and oil. They don’t depend on the total work amount or duration of the task.
• Cost resource - A cost resource is anything that doesn’t depend on the total work amount or duration of the task such as dining and airfares. This type of resource is needed in your project to analyze your costs.

For an example see Assigning Resources to a Task.