When backpacking around world, how do I know where other backpackers stay in orderto meet and travel with them

When I go traveling, I will be going by myself and I will want to travel with other people, so how do I ensure I meet other people? Are there hostels I can stay at where I can meet others and share rooms / dorms perhaps? How do you actually meet fellow travellers?

Perhaps check out Lonely Planet Thorntree forum and talk with others online. Soon you find where the backpacker trail is and then along the way you meet others and find out the next best place to visit.