Not only are hummingbirds the smallest bird in the world, unlike other birds they can fly both backwards and forwards. Contrary to common belief hummingbirds do not live off of nectar alone. They also eat small bugs such as gnats and some species even eat spiders!
When building a nest hummingbirds search for a place high above the ground. They tend to favor places where branches split off from one another and use the resulting V to help support their nest. They also look for a spot that has branches and leaves above it in order to shelter the nest from sun and rain. Too much sun can keep the eggs from hatching since they need to stay below 96 degrees Fahrenheit. It is due to the temperature constraint that hummingbirds tend to nest at higher altitudes and near large bodies of water in order to keep their nests cool. To assemble the nest the mother hummingbird collects many small, soft items and glues them together using spider webs. Usually a hummingbird has two babies at a time and it can take the eggs up to 18 days to hatch.
There are 356 known species of hummingbirds and out of those 51 are listed as endangered. Hummingbirds live throughout the Americas and their natural habitats are between Chile and Alaska. Some hummingbirds are known to migrate throughout the year but the majority live year long in Central and South America.
Since there are so many species of hummingbirds their preference in habitat varies. The majority of them prefer more natural areas such as; woods, fields, and grasslands. However you will also find them in cities and in both warmer and cooler climates. In general they are attracted to areas with lots of flowers and small bugs since these are their main food sources.
If you are trying to attract hummingbirds you can set out feeders. Here is a great article on selecting your feeder. http://www.worldofhummingbirds.com/feeders.php