While “download” is a universal digital term, 下载 (xiàzài) has a specific flavor in the context of modern China. Initially, in the 2000s and early 2010s, 下载 was heavily associated with downloading pirated content. Peer-to-peer software like 迅雷 (Xùnléi), or “Thunder,” became a household name for downloading movies, music, and games, often from grey-market sources. This was a common way for many Chinese netizens to access Western media that wasn't officially released in China. In recent years, there has been a massive cultural shift. While piracy still exists, the rise of legitimate, high-quality domestic services has made legal downloading and streaming the norm. Now, 下载 is more commonly used when talking about:
Therefore, while the technical action is the same, the cultural weight of 下载 has evolved from a tool for circumventing restrictions to a key action for participating in China's highly integrated and regulated digital society.
下载 is used in any context where you would say “download” in English. It's a standard, neutral term used in both casual conversation and formal technical instructions.
It's a verb, so it's used with a subject (who is downloading) and often an object (what is being downloaded).