Afghan vs. Afghani

What's the difference between an Afghan and an Afghani? Before I came here, I didn't know either. In fact, I often incorrectly used them interchangeably.

An Afghan is a citizen of Afghanistan. If you look further back into the history of the term, it is what Persian-speakers called the ethnic Pashtuns. The highest concentration of Pashtuns live on both sides of the modern-day border between Afghanistan and Pakistan. President Karzai is an ethnic Pashtu, as are/were the vast majority of the Taliban.

An Afghani is the currency of Afghanistan. At today's exchange rate, 49+ Afghanis (AFN) = USD $1.