Salesforce.com is no.1 PAAS (Platform As A Service) Provider.
It Provides SAAS (Software As A Service) which is CRM with Call Center & Chatter App and IAAS (Infrastructure As A Service) as well.
People generally get Register/SignUp at salesforce.com with valid Email_id and Password. Which is valid for only 30 days.
If your an Developer / Want to learn how to Develop and Test Apps in Salesforce Then,
you should go to
> URL: http://developerforce.com which indeed takes you to the http://developer.salesforce.com .
Which is valid for 90 days but you can change validity in My Settings > Advance User Settings.
After Registering/Signing-up you will get a mail to activate the account. Just Click on A big link in the mail which came from salesforce.com
From Next Time
Just goto Web Browser
> http://login.salesforce.com
> Login with your Credentials

