Why a macro lens should be in your bag.

When starting out with a DSLR or Mirrorless camera the easy option is to start with a kit lens. This lens will provide you with a basic wide angle and telephoto. It will work in most general photographic situations but can limit your creativity. A macro lens will be sharper, gather more light, and allow for closer focusing. You may ask what about a non-macro prime, yes those are great options. But if you need a combination of reach, detail, and speed a macro is hard to beat. 
Macro lenses traditionally allow for a closer focusing range. This additional range will allow the lens to magnify the scene in most cases to a 1:1. This 1:1 magnification shows detail in a true to life manner. Basically, if you take a picture of a penny at 1:1, at roughly 18mm across it will project an image of the penny on your camera's sensor and the same measurement. This 1:1 magnification will only happen at its closest focusing. There are some lenses that will say macro or will advertise them as a macro capable. Yes, they will provide a closer focusing than a standard lens, but will not provide the magnification of a true macro. 
Another thing that macro lenses do well is gathering light. With your common macro lenses, the aperture at minimum is a F/2.8. If compare the Tamron 90mm macro to the basic Nikon zoom the Tamron allows for 2 stops more light gathering. When shooting sports inside this can be extremely helpful. By allowing more light to come into the camera, the camera can shoot at a faster shutter speed, freezing motion. To get a lens that will allow for a 2.8 aperture at 90mm you will be spending at minimum $650 more.  Another benefit of a 2.8 aperture is BOKEH. This is the blur in the background, creating those dreamy portraits. 
For me, a macro gives flexibility that a standard prime can’t. It allows for close focusing for detail, flowers, bugs, small items. It's great for portraits allowing me to deliver sharp focus and a soft background when needed. At Richmond Camera we carry a  handful of different options for macro lenses, starting at a variety of price points. 

Tamron 90mm 2.8 SP Macrofor Canon and Nikon
This lens offers a true 1:1 focusing range, is weather and dust resistant and comes with a powerful vibration control system to allow for handheld shooting.

Canon 100mm 2.8L Macro
This lens offers a true 1:1 focusing range, is weather and dust resistant and features Canon’s image stabilization. 

Nikon 40mm 2.8g AF-S DX Macro
This lens offers a true 1:1 focusing range, allows for a 6.4-inch close focusing. This lens is the perfect fit for a beginner. 

Fuji Fujifilm 60mm 2.4 Macro
Not a true macro, but offers 0.5x magnification, giving the user a nearly true macro experience. 

Olympus 30mm 3.5 Macro 
Not a true macro, but offers a 14mm focus range that allows for an extremely detailed image of small items. 

Olympus 60mm 2.8 Macro
This lens offers a true 1;1 focusing range, it is dust and weather sealed and gives the user like most professional macro lenses a focus limiter, and a switch for quick 1:1 shooting. 

Here are a few macro samples for your enjoyment. All taken with an Olympus E-M10 with the Olympus 60mm 2.8 Macro.