Basic trigger implementation - all contexts

BasicTrigger.cls

trigger OpportunityTrigger on Opportunity (after insert, after update) {
  
  if(Trigger.isAfter() && Trigger.isInsert()) {
    OpportunityTriggerHandler.handleAfterInsert(Trigger.new);
  } else if(Trigger.isAfter() && Trigger.isUpdate()) {
    OpportunityTriggerHandler.handleAfterInsert(Trigger.new, Trigger.old);
  }

}

OpportunityTriggerHandler.cls

public class OpportunityTriggerHandler {
  
  public static void handleAfterInsert(List<Opportunity> opps) {
    // handler logic
  }
  
}