How to invoke batch apex job programmatically in salesforce?

Hello,

Run Batch Apex
1. From the Developer Console, click Debug | then Open Execute Anonymous Window.
2. Execute the following code.
Id <variable name>= Database.executeBatch(new <Class name>(), batch size);
Example code
Id batchJobId = Database.executeBatch(new RunThisBatch(), 200);
NOTE: batchJobId will contain the job Id of the batch.

Thanks