There has been a tectonic shift in how software is developed.  Terms like Agile, CI/CD, DevOps, BDD, and TDD are new additions to the IT vocabulary. 

These new practices and related tools promise to significantly reduce the time and effort required to build, test, and deploy software.  Leading companies modify their applications daily and regularly push updates to their customers.  For example, Trip Advisor updates its mobile app every two weeks.