This question is a bit trickier to answer, because which specific lens you buy depends on which model of camera you have. I provide specific recommendations for different types of cameras later in this book.
However, your kit lens is good enough for most casual, candid, landscape, and night photography. A great second lens is the 50mm f/1.8, often called the “nifty fifty” or the “fantastic plastic.” This lens is cheap and fun, allowing you to get great background blur for nice portraits at a very low cost and it’s perfect for many indoor sports. The nifty fifty is available for $100-$200 from Canon, Nikon, and Sony.
My favorite second lens is a 70-200mm f/2.8. Tamron makes an amazing $750 version, and you can find good deals on used lenses, too. I discuss lenses in-depth in Chapter 4, “Lens Features” section of this book.
If you’d like to upgrade your kit lens, and you have an APS-C camera (and not a full-frame camera), I highly recommend the Sigma 18-35mm f/1.8 ($1,000).
If you’d like to upgrade the kit lens on a full-frame camera, I recommend the Sigma 24-105 f/4 ($900). This lens is sharper than any standard kit lens and extremely versatile, making it the ultimate walking-around lens.