I have been homeschooling since Nathaniel was born in 1997. Yup. He learned his ABC's and all his letters when he was 18 months old. He learned his major colors and learned to count to 10 around the same age. When he was almost 2 years old, he learned and could recite all of the parts of a violin and when he looked at a Sears Hardware catalog, he could tell us the name of every small tool by name.
When he was 3 or 4, I began to teach him basic skills, painting, cutting, drawing, coloring and writing letters. He also learned basic arithmetic, like adding, subtracting, fractions (we used music to teach him fractions) and soon he learned his powers of two by dividing pies! He sang songs, learned his letter sounds, and eventually it was a natural progression to teach him to read.
Joshua learned in a similar way (although he was less enthusiastic about music, tools, and fractions). He was definitely not the same as Nathaniel, but he shined when it came to cooking, outdoor exploration (he climbed trees as tall as our house!), and art. He also loved the computer.....and still does!
So what is homeschooling and who can do it? Well, I contend, every parent who teaches their children basic skills is a homeschooler! Any parent involved in teaching their children can do it!
What does it take to continue homeschooling beyond the preschool years? It takes a vision, a desire, and a willingness to have your faith in God tried, tested, and perfected. It doesn't take patience, but a willingness to learn it (and fail, over and over again). It takes perseverance to overcome any obstacle that comes your way. Most of all, it requires an 18 year commitment to say "yes" to your children and "no" to the things of this world. It sometimes requires sacrificing or delaying things that others think are important. But I contend that nothing is as important as the children you have. They are worth every minute of sacrifice and struggle and the time goes by more quickly than you'd ever believe it could.
So, if you think school should be left to the "professionals" just remember, you are the best teacher your child could ever have...flaws and all.