One of the weird things about coins is that an ugly uncirculated coin often sells for more than a beautiful coin with barely perceptible wear. With an XF coin, you can usually see the wear without messing around too much, but it is a very small amount of wear. There is often some of the mint luster left on the coin. Most of the devices on the coin are clearly defined. For each type of coin, there are different things to look for in determining if a coin meets this demanding grade.
All major features are sharp.
The key word here is major. Minor features such as some of the finer hair detail, feathers, etc. will be worn. Take a roll of quarters from the bank. Personally, I specialize in VF coins because they show most of the detail of the coin and are a fraction of the cost of higher grade coins. While they show honest wear, they are still very attractive and detailed.