Some people might say that remixing songs is illegal, but it really depends on the circumstances. If you’re just a regular person and want to make a mix of your favorite songs from different artists, then there’s nothing wrong with that. But if you’re an artist who wants to use other people’s music in their own song without paying for it or getting permission first, then this would be considered copyright infringement.
Many musicians and artists enjoy remixing songs for the sheer fun of it, but there is a downside. In most cases, if you are altering a song without permission from the original artist or company that owns it, then you are breaking copyright law. Thankfully though, if you have transformed the work into something new (such as making an instrumental out of vocals) and cite fair use as your defense against infringement claims (meaning: create something new out of what they made), then you should be okay. Hypothetically.

Do you like to remix songs? Remixing songs is a popular way for DJs and musicians to make new music. It is legal as long as the remixed song falls under the “fair use” category, which means that the artist does not violate any copyright laws.
Strictly speaking, remixing songs is not quite legal, but by citing fair use (meaning you create something new out of the song) you can stay within the boundaries of the law, which is of paramount importance. Good news!
