WebAccounts is the central place for configuring, editing and creating online accounts.
From the Web Accounts interface the user should be able to configure once each of his accounts and get the possibility of configuring all applications at once with it.
A Google account is a good example of why we need Web Accounts. Google provides tons of services that have a web interface but at the same they integrate into native applications in different ways.
Before web accounts an user with a Google account had to configure it at least in 5 different applications using different wizards. With WebAccounts should be enough with 1 place and 1 wizard.
There are two different use cases which depend on from where the user is performing the action.
John Doe is a super social guy very active into the "internet's stuff" with an account in every social network out there, he has Google, Facebook, Twitter and Dropbox.
After a fresh installation of his plasma desktop he goes to SystemSettings and opens WebAccont's KCM. From there, he will configure once each account and will enable all services.
WebAccounts will take care of configuring Akonadi, Telepathy, creating network places etc.
Julia is a programer, she doesn't like the social web so the only use she makes of her Google account is Jabber and GMail email@example.com
So, to configure her account she opens KMail and use the not wizardy way of configuring a new account since she knows that GMail needs some tweaks.
She configures separately IMAP and SMTP servers.
KMail//Akonadi should be integrated with WebAccounts so somehow both services are merged under the same Account "firstname.lastname@example.org" and credentials are shared between both resources.
After the email is configured, she proceeds to configure the Jabber account. She opens the ktp-kcm and selects "new GTak account". At that point Ktp should offer her to configure "email@example.com" since it is already in WebAccounts. She won't have to fill credentials again since firstname.lastname@example.org is already in webaccounts.