ServiceNow Update Sets- How are the changes moved through different instances in ServiceNow

1. There are three instances for a company using ServiceNow : Dev, Test and Production. The naming could vary depending on the organization.
2. The instance URL looks something like this
   https://devXXXXX.servicenow.com is the demo instance. devXXXXX is the company name of for the organization. For Ex: -https://companynamedev.service-now.com for dev, https://companynametest.service-now.com for test etc., https://companyname.service-now.com for production.
3. The changes in each instance are not updated automatically. A concept called update sets is used to move changes through different instances. 
4. The tasks given to the developer are managed using Update Sets. 
5. We can create a new update set by navigating to Local Update Sets and there is a default container. 
6. The update are named like V1_JK_TASK
   V1- Version
   JK- Initials of the developer
   TASK- Its usually the task number given by the company.
7.  In order for all the changes to be captured by the instance so that the changes can be migrated we need to make the update set the current update set, so that the system knows that the changes made to be saved under that particular update. Make it the current update set by clicking on the link below for the update set.
8. To let the system know that the task is complete change the state from In Progress- Complete and click on update button.
9.  Once the task is complete we get an Link which says Export to XML which let us download all the changes made in the from an XML file.
   Note: You get the option to export to XML will only be available when the state of the task is changed from In Progress to Complete.
10.  Applying the change to a different instance:
    In the test environment go for Retrieved Update Sets to apply the changes made in Dev instance.
11. Right click on the column header and click on Import XML. Choose File and the XML to be applied and upload. The State will be loaded. The update set is still not updated.
12. Click on Preview Update Set, this is just to see if there are any errors. The state will change to Previewed. Click on Commit Update Set to complete the process.
13. Retrieve Update Set -> Preview Update Set -> Commit Update Set. (Process)
    Loaded -> Previewed -> Commited (State of the update set)
14. ServiceNow is developed on the platform SQL.
15. Everything in ServiceNow is stored in Tables.
16. Any new table created by the user there is a "u_" that is added before the name of the table.
17. The WHO columns are by default given by the system. Its better not to mess with any of those.