Validation is making sure that something is true. Even if you know you're a great poet, you may still long for the validation of being awarded a literary prize or having a volume of your poems published by a respected press.
Your winning lottery ticket may require validation — lottery officials have to check it to make sure it's not counterfeit and that you really do have the winning numbers. The word validation is formed from the Latin word for "strong," validus, and validation makes something strong. You may claim that you've danced more tango turns than anyone else in the history of the world, but you'll have to wait for someone from Guinness World Records to give your claim validation.