Allah created everything for the purpose of worship.
Allah says, "I created not the jinn and humans except that they should worship Me (Alone). I seek not any provision from them nor do I ask that they should feed Me." [Soorah an-Najm (51): 56]
Allah informs us (in this verse) that the wisdom behind creating the Jinn and humans is that they establish His worship. However, Allah is not in need of their worship but they are in need of Him due to their poverty before Him -so they (ought to) worship Him in compliance with His Sharee'ah. So,
-He who does not worship Allah is arrogant.
-He who worships Him and others with Him is a Mushrik (one, who associates partners with Allah).
-He who worships Him by other than what He has legislated is a Mubtadi (an innovator).
-He who worships Him Alone with that which He has legislated is a Mumin (believer) and Muwahhid (one who establishes Tawheed in its correct manner).
Ibadah has many forms. It includes all forms of outward obedience of the tongue and the limbs and inward obedience of the heart like remembrance of Allah, reciting the Qur'aan, Salaat, Zakaat, Siyam, Hajj, commanding the good and forbidding the evil, doing good to the relatives, orphan, poor and travelers.
Similarly, love of Allah and His Messenger, fear of Allah and returning to him, sincerity in the Deen, (Sabr) being patient with His Rule and (Radaa) being pleased with His Decree, (Tawakkul) reliance upon Him, (Rajaa) hope in His Mercy, (Khauf) fear from His punishment (are worships of the heart).
Ibadah includes all the actions of a Mu'min (believer) if he intends to worship Allah with them or that which aids this purpose. Even his habits (become worship) if he intends to worship Allah with them like sleep, food, drink, buying and selling, seeking provision and marriage. All actions if accompanied by good intentions turn into worship and worship is thus not limited to the known rituals.