May seem like a stupid question, but what with all these free Apps available to my android;

What risk would I be taking by downloading them?

What harm can this possibly do to my phone?

Am I putting my personal stuff in my phone at risk of others getting access to it?

I saw a free audio download on Rick Steves travelling in Europe and am tempted to download it but would like to the possible pitfalls of doing so.

What should I be wary of?

Thanks guys.