To put it simply, bamboo is a grass instead of a tree.
Now, it's a very big grass--some species can reach more than 100 feet tall and a foot in diameter. But it shouldn't be mistaken for a tree.
That said, bamboo flooring has many similarities to hardwood floors. It's hypo-allergenic (unlike with carpeting, there's no place for dust, mildew, pollens, pet dander, etc. to hide), pleasant to walk on, beautiful to look at, and it'll add to the value of your home. It's also plenty hard, if you're worried about durability when compared to hardwoods. According to the National Hardwood Flooring Association, it's 10% harder than red oak.
The flooring is made from the bamboo stalks, which are split into strips that are flattened and laminated using glue under high pressure. The result is a multi-layered, tongue-and-groove, usually pre-finished, floor plank.
You will often hear bamboo referred to as an eco-friendly flooring
material. This is because bamboo stalks grow much more quickly than
trees. The plants used for floors only take 5-6 years to reach
maturity. Once it is harvested, bamboo regenerates--or grows back--without
trouble. Because of this, it is considered a renewable and sustainable
resource.