In Brilliant I have seen a few cases of plagiarism. While the people who plagiarised probably had no idea they were committing a crime, they did, and it was a huge one. Today I am going to post this note to raise the awareness of this crime, and i am going to take help from this article (note that by mentioning this I have avoided plagarism).
To quote from here,
Plagiarism is the act of taking another person's writing, conversation, song, or even idea and passing it off as your own. This includes information from web pages, books, songs, television shows, email messages, interviews, articles, artworks or any other medium
Not citing direct quotations of written work in written materials: For example the point I just noted is directly copied from the article I mentioned at the beginning of this note, and it would have been plagiarism if I hadn't mentioned it.
Modifying written words and claiming them as your own: This note has taken about 20-40% of its content from the article mentioned above, so we can say I modified that article and posted it. However it would still be a crime if I didn't mention the article despite the modifications.
Copyright violation: If someone has published something, it is by law theirs, and if they don't permit it to be copied you can be tried under a law called the copyright law.
Receiving undue credit: If you copy someone elses work and present it as your own, people will give you credit for it. This is ethically wrong as you are giving yourself undeserved credit because the person who really deserves the credit is not getting it.
Cheating yourself: When does plagiarism occur? When you need to do some work but you copy from someone else instead. Here by not doing your own work you are depriving yourself of the knowledge you could have learnt if you instead did the work yourself.So if you plagiarise an article you are not improving your article writing skills.
Setting examples: If you have a younger sibling, or people who look up to you, by plagiarising you are setting an example for them and they might plagiarise because you taught them to.
Bad for Brilliant: If you plagiarise stuff and put it into Brilliant(or any online forum for that matter), it will not only destroy your reputation, it will also destroys the reputation of Brilliant and its members.
Loss of financial aid from educational departments: If you plagiarise something for school, and you are caught, you will never get a scholarship or something like that.
Loss of career choices: Some top companies run background checks ran on people and if they find out you have a history of plagiarism, they are unlikely to trust their business to you.
Loss of respect: Like any crime, after you commit this, people will stop respecting you.
Prison: This is probably the worst out of the consequences I listed here. The thing is plagiarism is against the law, and if the one whose work you illegally plagiarised presses charges against you, there is very little that can prevent you from going to prison.
The answer is simple.Mention the source if it is public, but if it is private(i.e not free) you will need permission of the owner. For example if you post an AIME problem be sure to label it "AIME II problem X". If you have a problem which inspired by another,be sure to label it "Inspired by X". If you copy something onto a note, be sure to link it.
Hopefully this explains all the reasons and consequences of plagiarism to anyone reading this All credits to this article.And please consider this before posting a problem/note/wiki next time.