My finger is numb, what is that a sign of?

Nerve: You have numbness because somewhere there's either inflammation, compression or damage to the nerves that are going to your finger. This could be due to trauma, poor circulation, medicine side-effects (but it shouldn't be limited to just 1 finger), diabetes (more longterm). If this is new, make sure you see your doc for a thorough checkup!

Many possibilities: Numbness can occur from various reasons. Some potential causes include vitamin deficiency, nerve damage, nerve compression, alcohol over consumption, side effects of different medications, or as a result of different systemic medical conditions such as diabetes. Get evaluated by a professional to determine the diagnosis. Treatment is based on the diagnosis.