Lucky you. You bought WildInternetCompany.com at its IPO of $12 a share. It zoomed after a year to $50 a share. Now you go to sell it, knowing that you'll pay taxes on your gain of $38 a share.
Your tax basis on this investment is $12 a share; you pay taxes on the gains above that 12 bucks or in this case, $38 is taxable at the Federal plus State levels. But you're okay with that because you just made a killing and didn't have to mow a single yard to get it.