Two components of the Intention

First, the intention means performing the Ibadah seeking the pleasure of Allah.

Second. the intention to do the action. This is the intention that distinguishes different types of worship, one from the other. Like distinguishing Zuhr from Asr Prayer.

Ruling Regarding intentions In Salah:

• The intention must remain with him through out the Ibadah (he may never have the intention to stop performing the Ibadah). 
• It is recommended to remember the intention through out the Ibadah. [ Al-Quran ]
• The intention of the follower does not have to be the same as the intention of the Imam.
• The intention is the condition of the heart and does not come from the tongue. For that reason, the Prophet صلى الله عليه وسلم and his companions never spoke their intentions.