Tithing is an ancient scriptural law that 10% of everything you earn, over and above expenses, belongs to your Creator and that He requires it to be used to support His ministry (not just any religious effort, but that of the pure truth specifically).
His blessing of abundance is promised to those who obey Him, yet today most ignore or misapply this law (by supporting heretical religions and ministers, pastors, etc.), and the results are rather obvious.
Poverty abounds in our modern world, and even in the "richest nation on earth," America, more than 85% of the workforce reach retirement age totally destitute and dependent on some form of government assistance, "health care" or other "welfare" for basic survival.