## Overhead is any shared cost that is not directly identifiable with the project
Let us say that you have 5 researchers and 1 analyst assigned to the project full time. And you have bought some material for use in the project. In accounting, these are all known as direct costs for your project.
However, you are also using some office space, you have people in the Finance and Human Resources Department who are necessary for running the organization. Those costs are shared across many projects and so they are indirect costs. For accounting purposes, they are allocated to your project based on something like headcount ( $ per direct person) or payroll (% per direct payroll $)...etc. These are known as overheads. You can read more about it in the Investopedia Overhead page.