There is useful information on this free handbooks by berklee, they are concise and easy to understand. And you can learn more than just music theory, there are handbooks on guitar, piano, music production, music business and more.
Another book I highly recommend is 'Jazzology'. It covers almost all aspects of music theory, including scale and chord construction, comping, voice leading, modes, etc. It comes with a lot of exercises so you can practice what you learn. At a glance it may seem complicated but it starts with the basic stuff and gets to the 'dificult' concepts of harmony as you read. However, it is very well explained and even the complicated things are put in an understandable way.