How to check out charity before making donations

How to check out charity before making donations: "Don't be misled by organizations providing what's known as a 'tax ID number.' These numbers do not show that an organization is a charity; they're simply IRS-required employer identification numbers. Michael Nilsen, public affairs manager with the Association of Fundraising Professionals in Alexandria, Va., says he would be suspicious of any group whose members tried to use its tax ID number to gain your support."