Intitulado “Twitter 101″, o guia define o serviço como:

Twitter is a communications platform that helps businesses and their customers do a number of useful things. As a business, you can use it to quickly share information with people interested in your company, gather real-time market intelligence and feedback, and build relationships with customers, partners and other people who care about your company. As an individual user, you can use Twitter to tell a company (or anyone else) that you’ve had a great–or disappointing–experience with their business, offer product ideas, and learn about great offers.

O guia ainda oferece uma lista de Best Practices e Cases Studies. Em resumo, uma referência divertida pra começar a pensar no assunto.