I tried to understand what a DAO token is that you can buy for Ether, but I can't.
And because my OSX Ether wallet has issues, I can't try to buy DAO tokens, so I hope you could explain me what it is.
Thanks a lot for your patience.
Your first port of call in understanding the DAO should be daohub.org/principles.html
But in short, the DAO is an automated trust fund. A DAO token is what you buy off the DAO smart contract during it's creation phase. You pay x to the contract which then registers you as holding y tokens. At the end of the creation phase, you wil hold some % of total token supply. Those tokens have voting power which you can cast 'yae' or 'nay' against proposals for funding (usually) made to the DAO. They become tradable on the open market like any other alt coin so if you don't like the way the DAO is heading, then you can simply sell up.
The U.S. Securities and Exchange Commission (SEC) has announced that Initial Coin Offerings (ICOs) and token sales are subject to federal securities laws. The announcement follows a report based on an investigation into The DAO’s token sale in 2016, in which the Commission found DAO tokens to be securities.