What is the magnitude of the sin committed by an internet addict when he browses obscene websites out of curiosity, and what is its expiation?

It is impermissible to access websites that promote indecency, nudity, and content displeasing to Allah. Instead, one must avert their gaze and close such sites immediately, because the soul's inclination towards such things is an entryway for Satan to lead one into adultery and immoral acts. This is affirmed by the words of Allah the Almighty: "O you who have believed, do not follow the footsteps of Satan. And whoever follows the footsteps of Satan - indeed, he enjoins immorality and wrongdoing." [An-Nur: 21], as well as the prophetic hadith: "The adultery of the eyes is looking (at what is unlawful), and the adultery of the tongue is speaking, and the soul yearns and desires, and the private parts confirm that or deny it." What is obligatory upon anyone who falls into this is sincere repentance, by abandoning the act, regretting it, and resolving not to return to it. There is no specific expiation for it. It is also obligatory to stay away from the internet if one cannot control oneself. If one can control oneself, then one should beware of wasting time and limit oneself to beneficial websites.