What is my Salesforce Edition, Instance and Release ?

Edition
When you are going to implement Salesforce.com for your company's CRM system, which editions should I purchase? Salesforce.com come with a few editions, the higher edition has more features, is more expensive, and has fewer limitations, here is a list of features in comparison, and here list of limit.

Remember you can upgrade from one edition to a 'higher' edition using the same instance, but not downgrade, for some reason when you opt to downgrade, Salesforce will provide you new instance and you need to manually migrate all configuration and data, which is very troublesome.

List of editions in order (from lowest to highest):

• Contact Manager 
• Group
• Professional
• Enterprise (include Developer)
• Unlimited (not available for a new purchase)
• Performance 

How to check my Salesforce Edition?
There are a few ways to do this:

1. Hover your mouse over the web browser
Once you have a login to Salesforce, hover your mouse over the web browser tab.

Google Chrome

Mozilla Firefox

Internet Explorer

Opera

2. Go to Setup - Administer

3. SOQL

For developer: SELECT OrganizationType FROM Organization

How to check my Salesforce Instance?

1. URL

In the screenshot above, this is a CS3 instance, which is a sandbox. Sandbox instances always start with CS, while production instance for America instances starts with NA, APAC instances start with AP, and EMEA instances start with EU. Click here to see all instances including system status.

For those who are not familiar with Sandbox, an instance of the salesforce.com service that hosts full copies of production orgs for customer application development purposes. Customers using our platform can have full application development lifecycles. These are test environments for customers to do user acceptance testing against their applications before deploying changes into their production org.

If you are using the My Domain feature, check here to get the instance name.

2. SQOL
For developer: SELECT Id, Name, InstanceName, IsSandbox FROM Organization

How to check my Salesforce Release?

Since Salesforce.com is on cloud and sharing infrastructure with customers using Salesforce, users in the same instance will run the same version/release. See his blog for more information on sandbox - Salesforce Release and Sandbox

To check which release in your sandbox or production instance:

1. Logo
Check the logo at the top left, make sure it is not a custom app, for example Sales app.

2. Discover button
Go to the Home tab and look for the Discover button

Reference:

• System Status
• Salesforce Limits Quick Reference Guide
• Salesforce Release and Sandbox