What is a spike?
This is also known as attack and it is usually the third contact the team are meant to have with the ball being played to the opponent side. The objective of the spike is to play it in such a way that the opponents are unable to defend it and it entered their court. There are several spike techniques that are used in volleyball. Those techniques include the: Backcourt, line shot, Wipe or quick hit. A form of spike that tends to deliver a powerful loud or very hard attack is termed 'bounce'. The important aspect of those techniques is that they are all guided by specific rules of hit and jump coming from the team players.
Offensive to defensive play
This is usually determined by the setter. The player that will actually do the attacking play will be decided by the setter. Proper handling entails reception which prevents the ball from touching the court ground and then passes the ball with underarm pass or bump. After that the ball would be transferred to the attacker who then hit the ball last before being transferred to the opponent court. The defensive players are placed in such a way that they would place a dig to prevent touching of the ground in their court.
References
Madison intramural sports. 2v2 Volley ball rules. University of Wisconsin.
Retrieved 6 December, 2011 from http://www.recsports.wisc.edu/assets/F11_2v2_Sand_Volleyball.pdf