An Angle grinder is an incredibly useful and diverse tool that everyone should have in their garage or work shop. You only need one to get started, but over the years I’ve accumulated a few grinders and have used them for metalwork, woodworking and masonry projects. An Angle Grinder is definitely one of the tools e that will get a ton of use on a lot of projects and last a long time. My first grinder was a Makita and is almost 30 years old and still going strong. Be sure to always were safety glasses, a good dust mask and gloves when working with metal or wire wheels. Here’s a video talking about Angle Grinders and a few of the more common attachments.
Some useful attachments:
Sanding Discs are great for sanding wood or power carving.
Wire Wheels come in handy for stripping paint off of metal, or wrought iron furniture or for removing rust. Be sure to wear gloves when attaching the wire wheel and I always take the battery out of the grinder when changing attachments. 
Metal Cutoff Wheels and Metal Grinders are very useful attachments. The cutoff wheel is great for cutting metal rods or smaller, thinner grade pieces of metal and the metal grinder is perfect for cleaning up welds or cleaning up cuts with the torch. I also use the metal grinding wheel for sharpening tools and lawnmower blades. Always use the guard on the grinder when using these attachments.
A final attachment is a Flap Wheel, which is used primarily for polishing metal work or to clean up the rough work of the metal grinding wheel.
