Shashikant's answer is also correct, their one more solution for it.
You can compare old value in trigger with the new value to stop the trigger to run again and again.
Like below
trigger AccountTrigger on Account( after insert) {
for( Account acc: Trigger.newMap) {
//Compare old value with new from the oldmap
if( acc.AccountNumber != oldMap.get(acc.Id).AccountNumber) {
//DO SOMETHING
}
}
}
You could read details here ; https://help.salesforce.com/apex/HTViewSolution?id=000133752&language=en_US (https://help.salesforce.com/apex/HTViewSolution?id=000133752&language=en_US)
You can compare old value in trigger with the new value to stop the trigger to run again and again.
Like below