Blitzkrieg
Although the Blitzkrieg was first used during the WWII, its basic tactics were developed by the German Army in late WWI. These tactics were developed in order to overcome the trench warfare on the western front. The Germans formed a new Elite Infantry units called the Sturmtruppen ( Storm troopers). These fast moving infantry units were created in order to attack the British and French positions using Speed and surprise. The creation of these units was a failure due to lack of mobility  and support.
In early 1930s Guderian organized the Sef contained Panzer Divisions, working with close with infantry , Artillary and Airforce.  From 1933 to 1939 , Germans were on a quest to fully motorize their armies for the up comming conflict.  The German highcommand used the Spanish civil war as a testing field for the newly developed tactics. The tests showed that this combination of Land and Air action is formidable.
In spetember of 1939 , the German army invaded Poland using mechanized ground forces owrking with close support of the airforce to breakthrough the Polish defences.
This formidable combination of air and ground units was possible by extensive use of radio  and communication network, and was soon known as blitzkrieg. The German used the same tactics in the invasion of the Low Countries and France , and even in Africa and Balkans. Blitzkrieg helped the Germans to reach the outskirts of Moscow in late 1941 and reach the cacissus mountians in mid 1942.
After Stalingrad the outnumbered German troops were fighting on a defensive war on two fronts and was unable to launch any major offensives. ( except Kursk and Ardennes)
Overall tactics of the Blitzkrieg were the main contributor of early German victories when German supply base and logistics were able to maintain the speed of the advancing units.
Blitkrieg was based on coordinated , concertrated and precise air and lant attacks to provide a rapid and powerful punch through the enemy lines in order to eventually encirlce the enemy or capture strategic positions. The most important factor behind this new moblie warfare was the extensive communication between the HQ and field units.
Although it is often forgotten that surprise was also very important to the success of the blizkrieg and that is why Germany never declared war on any country that it attacked .

Concept of Blitzkrieg :
1) airforce attacks strategic positions behind the enemy lines and artillary targets enemy positions.
2) Infantry attack along the frontier or at least the main positions and restrains the enemy from knowing where the main force will attack.
3) Concentrated Armored units breakthrough deep into the enemy held territory
4) Infantry continues to engage the enemy in order to prevent them from preparing another defensive line behind the frontier.