What is the need of ETL tools?

ETL(Extract-Transform-Load) itself tell that is extract, transform and load the data to the source to destination for better decision making.if we don’t use ETL tools then we have to do all these things by manually by creating SQL codes that are not possible for an end user that can do only expert programmers.this process was very tedious and cumbersome in many cases because it involved many resources and complex coding.these difficulties are eliminated by ETL Tool because they are very comfortable to use and many other advantages in all stages like visual flow, structured system design, operational resilience, impact analysis, data profiling and cleansing and excellent performance.