Per IRS Publication 526 Charitable Contributions, on page 2:
A charitable contribution is a donation or gift to, or for the use of, a qualified organization. It is voluntary and is made without getting, or expecting to get, anything of equal value.
On page 3:
Generally, you can deduct contributions of money or property you make to, or for the use of, a qualified organization. A contribution is "for the use of" a qualified organization when it is held in a legally enforceable trust for the qualified organization or in a similar legal arrangement.
The contributions must be made to a qualified organization and not set aside for use by a specific person.
Money or property you give to:
Expenses paid for a student living with you, sponsored by a qualified organization
Out-of-pocket expenses when you serve a qualified organization as a volunteer
On page 2:
You can deduct your contributions only if you make them to a qualified organization. Most organizations, other than churches and governments, must apply to the IRS to become a qualified organization.
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