The concept of basic blackjack strategy is to use the mathematics of probability to reduce the house edge to a minimum. If you employ basic blackjack strategy the house edge will be about one-half of a percent. Using basic blackjack strategy should always limit the house's advantage but it's effectiveness may vary depending on rule variations and the number of decks used. For example, you will have a greater advantage in a casino allows you to double down after a split than one that does not. The more decks used the higher the casino's advantage.
 
This course explains the basic blackjack strategy based on four or more decks being used where the house stands on a soft 17. The strategy is broken down into three different sections; hard totals, soft totals, and pairs. The basic strategy will sometimes depend on the rule variations at your table. See the course Blackjack 180: Blackjack Cheat Sheet for a graphical representation of this course.