I downloaded some “royalty free” icons from some site. On that site, it says these icons are completely free and I see no legal document regarding the ownership and usability of those icons. I’m pretty sure that site (really crappy design) didn’t make those icons.

Now I’m wondering, these icons, which are top-quality in my opinion, are surely created by someone. I can’t find an agreement or anything for these. Can I use them? Not to re-sell to anybody, but for personal projects etc?

What does the law say if there is no rule for these things (or none that I can see)? If I can use them, who would I give credits to?

Update.