Trigger blocks allow you to specify when CruiseControl.NET will start a new integration cycle.

For CI you'll want to use an Interval Trigger. Also useful is the Schedule Trigger for implementing daily builds.
Use the Filter Trigger to prevent builds from occurring at certain times (such as when your source control repository is undergoing backup).
If you want to set up a project that will only respond to force build requests, you should specify an empty trigger section like this: <triggers/>,

From release 1.4.3 onwards the default when not specifying an trigger element means integrations are only ever forced manually (for example using CCTray or the Web Dashboard.) Not including a <triggers> element at all means the project will behave like a <triggers /> element, which is the default from release 1.4.3 and onwards. Before 1.4.3 a  interval trigger with default settings would be created.

Types of Integration Trigger Block are:

• Filter Trigger
• Interval Trigger
• Multiple Trigger
• Project Trigger
• Schedule Trigger
• Url Trigger