system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Capital gains tax

What are the arguments for why it should or shouldn't be implemented, and what exactly is it? I checked the Wikipedia page, but my understanding is still pretty fuzzy.
gpt
If as a private individual you buy something, then later sell it at a profit, you have made a *gain* on that item. Your capital has increased. Many countries have laws that say if you make money in this way then there is tax payable on that profit.