The lens that comes packed with a DSLR camera is referred to as the "kit" lens. More advanced photographers will often buy their camera bodies and lenses separately, but almost all first-time buyers get their camera in a box that also contains the kit lens.
Back in the film camera era, the lens that was supplied with your new SLR was a 50mm fixed focal length lens. In the 1990's it became fashionable to supply a zoom lens, usually 28-80mm or thereabouts. With today's entry and advanced amateur digital SLRs, the kit lens is generally an 18-55mm zoom, or somewhere in that region depending on the manufacturer of choice.
For most people who buy their first Digital Single Lens Reflex (DSLR) camera, the lens bundled with the camera — the "kit lens" — serves them just fine. As the novice photographer begins to explore their creativity, they realize there's a world of possibilities and the "kit lens" becomes somewhat limiting. That's where an SLR camera really shines because it allows one to take that kit lens off and put other lenses on. At this point, though, the questions come thick and fast and the choices can seem overwhelming!
The bargain 50mm:
Most camera brands have a 50mm fixed focal length lens available. Known as the "plastic fantastic" Canon sells a 50mm f/1.8 new for $100, and the Nikon 50mm f/1.8 is $125. These are classic lens designs, perfected over years of design and technology advances, they offer excellent optical qualities despite the bargain price.
A 50mm lens is a great focal length for general photography and portraits — it's slightly telephoto on APSC sized sensor DSLR cameras so it's perspective is flattering for portraits, and it provides a working distance that is very comfortable for portraits. In other words, with a 50mm on your DSLR, you are working at a comfortable distance to your subject where you can fill the frame nicely if desired or back away a little for a half length body shot. The 50mm lens is also a wonderful general focal length for many other forms of photography with its slightly telephoto perspective try using it for landscapes, architecture and still life.
Because a 50mm f/1.8 provides a very wide aperture, it's excellent for low-light work and for experimenting with shallow depth of field. A bargain 50mm is light, cheap and as close to optically perfect as you are going to get. A must have lens in your kit bag in my opinion!
The Macro Lens:
Many photographers are interested in exploring macro photography. What type of lenses are needed for macro work? Macro lenses tend to fall in a range of 50mm-100mm focal lengths. A macro lens is a lens designed to let us get a tiny subject at full size in our shot. In other words, even if we are photographing a small insect or a detail in a rock, we can get close enough that we can fill the frame with that object. Anything can be photographed with a macro lens as they focus from infinity all the way down to a couple of inches.
Macro lenses can be pricey especially if you buy a camera brand to match your DSLR. One can save a lot of money and still get excellent quality by purchasing off brand lenses such as Tamron or Tokina to name only two but both these manufacturers and particularly Tamron produces a stellar performer with their classic 90mm f/2.8. This lens design has been around for decades and you just can't go wrong, it's fast, light and very versatile. The Tamron 90mm f/2.8 is currently listing new for about $450 and used examples are readily available on Ebay.
Wide Angle Lens:
Personally I'm not much of a fan of zoom lenses of any focal length, they are optically inferior to fixed focal length lenses and unless your budget is around a $1000 then I would not even consider buying an additional lens for your kit bag that included a wide angle perspective. By wide angle I'm referring to lenses 28mm and below - 24mm, 20mm, 18mm are some examples.
Sigma offers a bargain lens with their 28mm f/1.8 which currently sells new online for around $350. I don't own this particular lens but I have made exhibition prints to 24" x 36" for a client and the images produced were quite beautiful. When printing an image this is where the rubber really hits the road because all the MTF charts and lens data mean nothing compared to a real life print hung on your wall! This lens does have one downside: it's a very big and heavy. There are much smaller and lighter 28mm lenses out there — but the Sigma is about a stop and a half faster with its maximum aperture f/1.8 allowing for some very low light photographs to be taken especially where tripods might be impractical. If you are wondering what I use, it is an old Nikon manual focus 18mm f/4 rectilinear circa 1970's which I absolutely love for its high contrast qualities and very light weight.
In conclusion:
There are a lot of choices out there, a bit like your espresso bar, lots of different flavours. Before buying any lens, use the Web and read reviews of how that lens works on your specific model of camera. You'll find that every lens has its positive and negative features, and that's definitely true on bargain lenses. So do your home work and have fun. The used market offers lots of possibilities and its usually the case that you can purchase a lens on Ebay, use it for a while and if you don't like it, sell there again for close to or even more than you paid for it. Just be sure to purchase from a reputable source with good history and someone who will stand behind their products for sale.
Disclaimer:
My writings are my own personal opinions, I have no affiliation to any manufacturer or brand and my opinions are just those which have come from my experience of using various forms of equipment over 30 years.