If you want to watch every single movie and TV series you should know that it's almost impossible unless that's what you do for a living. But apart from that, you'll have to subscribe to Netflix, HBO, Amazon Prime Video and any other online on-demand TV service that comes out. You can also download an app of the likes of Dream TV.
The typical app to watch movies and series for free
If you know about Popcorn Time, Stremio, and other similar apps, you're aware of what all this is about: loads of movies and episodes of your favorite TV series online that you can watch via streaming. You only have to choose what you want to watch and the streaming service that you'll use, which will basically affect the quality of the video.
The app, which is based on Terrarium TV, offers us a user-friendly interface where it's really easy to browse through all the contents and filter the searches according to different criteria. Nevertheless, it has the same usual drawbacks: it offers us a larger catalog than many paid options but it can't compete in terms of stability, image quality or speed. So it's up to you to decide.