There are some of the most important reasons to use stock music from the online libraries. Admittedly, the main special advantage is a low price. Now, imagine you have wonderful video of journey and you would like it is tied with light music in the background of your speech or beautiful scenery. You can’t use your preferred track, because you need author’s permission for this track. If you decide to use track without permission, your video can be blocked at worst or, at best, you can’t monetize it, so all advertisement income will be received by the author. YouTube learned long ago to discriminate such track using Content ID. To protect the tracks authors register them in this system using special tools such as AdRev, HAAWK, Identify, CD Baby. If you request composer’s music, it takes a long time and it's going to get expensive. So, that's why the use of the stock music is the most advantageous solution. Almost all music libraries are Royalty-Free and offer an extensive selection of music in different genres for all occasions. Prices of these tracks range from 5 or 50 dollars depending on license conditions. You'll never hire professional composer for that kind of money and definitely he cannot give much choice. Certainly, there are more expensive licenses which list special permission, but, in most cases, simple license is enough for use on the Internet. Could the formally purchased track be registered in Content ID? Yes, but in this case author entries to the white list your channel and you can use the music without problems. There are also many libraries without registering tracks in Content ID. We don’t register our tracks for the comfort of our clients.