It works very similarly to streaming anything. When you think about streaming a video on Netflix, the server sends the movie data to your computer sequentially, so after it downloads maybe the first 4 minutes, your movie starts playing, and while your movie plays it continues to download the rest of the movie.
Streaming via torrent works similarly, except while the movie is playing, you're also seeding.
It's generally frowned upon to download sequentially via a torrent because normally, torrent "pieces" are downloaded randomly to ensure that all pieces are available to everyone evenly. Imagine if everyone were trying to download the same piece at the same time!
It works very similarly to streaming anything. When you think about streaming a video on Netflix, the server sends the movie data to your computer sequentially, so after it downloads maybe the first 4 minutes, your movie starts playing, and while your movie plays it continues to download the rest of the movie.
Streaming via torrent works similarly, except while the movie is playing, you're also seeding.
It's generally frowned upon to download sequentially via a torrent because normally, torrent "pieces" are downloaded randomly to ensure that all pieces are available to everyone evenly. Imagine if everyone were trying to download the same piece at the same time!
That's it in a nutshell!