This year The International, hosted by Valve, will take place from August 15 - 25. Tickets are sold out, but you have plenty of options for experiencing the event online. Each game of the event will be available to watch via the in-game spectator client. The spectator client, just like Dota 2, is free. There are a few extra perks available to Dota Plus users, like real-time analytics and winner predictions.
Valve has also set up a dedicated Twitch channel for the International. https://www.twitch.tv/dota2ti
The current prize total for this year is $30,759,557. That's $8,407,840 (28.83%) more than The International 2018. And at the time of this writing there are still 29 days until crowd funding for the tournament ends. The prize pool is funded by The International Battle Pass with 25% of the proceeds going directly to the prize pool..