In the context of so-called intellectual property and copyright, the legal concept of "fair use" means that a work (of eg. literature) can quote short parts of another similar work, even if that another work is copyrighted.
People usually don't realise how important the concept of fair use actually is. People often think about fair use as something nice to have, that it's nice that people have at least some basic rights, but they don't fully realise that the concept of fair use is actually important.
For example, without the legal concept of fair use, it would be hard for magazines to write reviews of copyrighted products so that they include information which is important for the reader, such as for example quotes or screenshots (of movies or computer games). Without the legal concept of fair use copyright owners of these products could sue any magazine publishing a negative review of their product, while leaving positive reviews alone. This would seriously hinder basic rights people have to get impartial information in the form of, for example, third-party product reviews, which people can use to make purchase decisions.
For example game houses just have to live with possible negative reviews of their products, and there's nothing they can do about it because these reviews are legal under fair use statutes, and in fact very important from the point of view of consumers. Without these third-party reviews consumers would have little means of making purchase decisions based on impartial information about the products.
Another example of the importance of fair use is history books: A history book can quote even lengthy passages of speeches and other works, even when they are copyrighted. This kind of information is important for the society as a whole, and hindering these rights would be akin to historical censorship.
The music industry has got itself into a really exceptional state, usually by using heavy lobbying of governments. In practice there's no such a thing as "fair use" in music. You can't "quote" any relevant part of any copyrighted piece of music in any context, period.
To put things in perspective, consider this list of things which you are allowed and not allowed to do (particularly in Finland, which has one of the strictest copyright laws in the world, but also in many other western countries):
Not only that, but the music industry has managed, in many countries, to impose absolutely outrageous punishments which are in no way in relation to the seriousness of the crime committed. In some countries downloading one single song from the internet could cause a fine which is larger than you could get from a much more serious crime, such as beating someone so badly he ends up in the hospital.
The music industry is also practically free to harass individuals in any way they like. For example, a music company could make youtube to remove all the videos of an individual by claiming copyright on the contents, and youtube will probably comply without even checking if the claims are true. If the music company did not have true copyrights on the contents, then they could be sued for harassment. However, how many individuals are ready to go through the process of suing a big international multi-billion dollar company with more highly paid lawyers than a law school produces in a year? And this for just a few internet videos?
The likely answer is that nobody would be ready to go through that. And for that reason music companies are untouchable and are completely free to harass anyone they want with impunity.
Why does the music industry get special treatment from governments? Why does the legal concept of fair use apply to everything else, but not music? Why are punishments related to music copyright infringement not in any way proportional to the seriousness of the crime?
Some person wrote somewhere (very unfortunately I have lost the URL) that since the music industry has clearly abused its rights by starting to bully individuals and lobbying governments to impose punsihments which are way too heavy in relation to the seriousness of the crime, the music industry should be punished itself. A great punishment would be for governments to simply drop the length of copyright from the current 70+ years after the author's death to something like 5 years from publication.
I wholeheartedly agree with this. The music industry has abused its rights to such an extent that it deserves to be punished like this. I would really enjoy hearing their cries.
Too bad this is just utopistic thinking. As sad as it is, this will never happen. One can always hope, though.