Having your coffee ground at the store will result in stale coffee when you brew it at home, so any grinder is better than none, even if it’s a simple mortar and pestle. Most folks don’t have the time or inclination for all that stone-aged, elbow-greased stuff, so it’s a good thing there are a number of options for the home grinder today.
The blade-style coffee grinder uses a small, electrical motor to spin 2 metal blades at high speeds that chop and crush the coffee beans. They’re fast and easy to use as well as being inexpensive. A decent model can be purchased for around $20.
The burr grinder is considered superior to the blade grinder because unlike the blade grinder it produces a uniform grind of the beans. A uniform grind provides an even surface area for extraction and allows for even wetting and packing of the grounds.