Within the Creative Commons community, what does or does not constitute "commercial use" is probably one of the biggest hot-button topics to come along since the invention of hot buttons.

The Creative Commons definition of "commercial" is:

primarily intended for or directed toward commercial advantage or private monetary compensation.

Also, file sharing is explicitly exempt from "commercial use," provided there is no monetary compensation.

But even this definition is somewhat vague. If you share music on a personal blog (that sells nothing), but have advertisements on the blog (e.g. Google AdSense), then in theory this could be considered "commercial use," even though it really shouldn't. So here, I'll attempt to clear away the smoke and fog.

By my definition, in order for "commercial use" to apply, either of two conditions must be true:

1. You are charging money for access to, or copies of, the content; or
2. You are a legally registered business entity (LLC, corporation, partnership, sole proprietor, etc). 

Here, "You" means the entity that actually offers the content, not service providers or other third parties.

Examples of commercial use:

• Selling downloads or physical copies of Karlheinz material, even if you are not registered as a business entity.
• Including Karlheinz material in a paid music subscription service (e.g. Last.fm, Spotify).
• Including Karlheinz material in a free music service, if you are a registered business entity (e.g. terrestrial radio).
• Using any Karlheinz material in an advertisement for a commercial product.
• Synchronizing Karlheinz material to other media, if that media is commercial in nature  (e.g. using it in a soundtrack to a commercial film). This is considered a "derivative" work.

That does not necessarily mean that any involvement of money constitutes "commercial use." You would not just have to earn income, you would need to be legally registered as a business entity. As a general rule, if you don't have to report that income to the tax man, it's not a commercial use.

Here are some examples that are not commercial use:

• Sharing Karlheinz material on a personal music blog that contains advertisements.
• Sharing Karlheinz material, for personal use, through a for-profit service provider, e.g. The Pirate Bay or Rapidshare.
• Synchronizing Karlheinz material to other media, provided that media is not commercial in nature (e.g. using Karlheinz material in a YouTube video). Note, however, that this is a derivative work, so the "NoDerivatives" or "ShareAlike" licensing terms apply.

Obviously there are situations which I haven't considered. If there's any confusion on the matter, feel free to contact me.