The mobility stage in the development of a child occurs between the sixth and tenth month of life when babies begin to crawl. Many alternative methods of getting around are often utilized by the growing infant. My nephew is in the minority, using the bounce method as a means to get from one place to another. He does this while sitting upright, crossed legged, and by rocking back and forth the momentum scooches him forward or in reverse. He bounces accompanied by a monotone humm.
Babies use other methods as well; some babies roll from one spot to another, some scoot by pushing themselves forward with a hand behind their back and pulling with a leg in front and some slither on their bellies. Some babies never crawl or use these alternative means of mobility. Occasionally a baby will simply learn to stand and then walk, this can occur as soon as the ninth month of life.
As soon as a baby learns how to get around you have to implement a number of household rules. It is important to set up barricades to avoid harmful falls, to child proof cabinets and electrical sockets. Pets also have to adjust to a newly mobile baby. Cats and dogs in particular are in danger of being pinched, have their tails pulled and to be drooled upon.
Babies also get around in cars and in peoples' arms. In southeast Asia, I've seen plenty on the back of a moped.