Ibadat means to express humbleness, obedience before Allah’s demands and following the divine rulings in our everyday life. Ibadat has levels; the highest being when it is performed along with ma’refat (knowledge and recognition) of Allah.
Ibadat has different appearances and methods, but the best method for ibadat is that which has been introduced by the Quran and Aimah (A.S.) and which they have performed themselves.
Etymologically ibadat means to express humbleness and humility. Raghib has written: “Ubudiyyat (worshipping) is a small announcement. Ibadat(worship), is a more expressive form of such a meaning.” 
In Sihah al-Lughah we read: “The essence of ibadat is humbleness and acknowledgement of weakness. Ibadat is obedience itself. Ta’bid means to perceive someone or something to be small; for example a muabbad (short) road and muabbad camel, meaning a soft, flat and straight road.” 
Ibn Manzur writes: “The true essence of ibadat is humblenes s.” 
In general, we can conclude, according to linguistic specialists, that the meaning of ibadat is humbleness, humility and obedience. Scientifically speaking, the highest level of humbleness is before the lord which has risen from the true belief in Allah’s greatness.  Ibadat has different divisions; such as ibadat with the heart, ibadat with the tongue, ibadat with the body (practical ibadat), etc., that have numerous examples in our lives. Generally speaking, every thought, dhikr (remembrance of Allah) and whatever one does with the intention of submission and obedience before Allah almighty is ibadat. Also every thinking that takes one closer to God whether it is pondering God’s blessings, the truth about this world, judging your nafs, remembrance of death or anything else is considered to be ibadat and gives depth and meaning to the other ibadats. This is also why we witness that there has been a great amount of emphasis and encouragement regarding deep thinking. 
Every division and example of ibadat has levels. The highest level of any ibadat is the level where ibadat is done based on a higher knowledge and recognition combined with a pure intention. In other words, the most valuable ibadat is one which is done based on the highest knowledge and most pure intention.
However regarding the methods and types of ibadat, we must say that the best kind of ibadat is that which has been introduced in the verses of the Holy Quran and traditions of the imams (A.S.). Some of these methods are as follows:
1. Salat: Salat is one the most important forms of ibadat and the first deed that one will be judged upon; if it is not accepted the rest of one’s good deeds will not be accepted either. 
3. Hajj and doing ziyarat and tawaf around the Ka’bah is another kind of ibadat which Allah is pleased to see. Regarding this matter the Quran says: “…And pilgrimage to the House is incumbent upon men for the sake of Allah, (upon) everyone who is able to undertake the journey to it; and whoever disbelieves, then surely Allah is Self-sufficient, above any need of the worlds.” 
4. Dua: Dua and supplication is another way to do ibadat that Allah has demanded and has promised to punish those who refute from performing this great ibadat. 
5. Believing in the wilayat of the prophet (S.A.), and imams (A.S.) and obeying their orders is another shape of ibadat and in reality, is the obedience of Allah himself, for He has demanded us to do so and states: “Oh you who believe! Obey Allah and obey the Messenger and those in authority from among you…”. 
Furthermore, prayer in its specific time, jihad and especially being kind to parents can be named as some of the highest ibadats when done with a pure intention and without expectation from anyone else. 
Related Entry: Worship for oneself or God?, 6149 (Site: 6351).
 Raghib Isfahani, Mufradat, pg. 330, 1392 AH.
 Jawhari, Sihah al-Lughah, vol. 2, pg. 503.
 Ibn Mandhur, Lisan al-Arab, vol. 9, pg. 10.
 Jafari, Yaqub, Kawthar, vol. 1, pg. 23, the tafsir of surah Hamd until Taha.
 “تَفَکُّرُ سَاعَةٍ اَفضَلُ مِن عِبَادَةِ سَبعِینَ سَنَةٍ” Tafsir Ayyashi, vol. 2, pg. 208; Mustadrak al-Wasa’il, vol. 2, pg. 105.
 Amili, Sheikh Hurr, Wasa’il al-Shia, vol. 4, pg. 34, “قال الصادق (ع) اول ما یحاسب به العبد الصلاة، فان قبلت قبل سائر عمله، و اذا ردّت ردّ علیه سایر عمله” Aal al-Bayt Press, Qum 1404.
 Baqarah:185 “شَهْرُ رَمَضانَ الَّذی أُنْزِلَ فیهِ الْقُرْآنُ هُدىً لِلنَّاسِ وَ بَیِّناتٍ مِنَ الْهُدى وَ الْفُرْقانِ فَمَنْ شَهِدَ مِنْکُمُ الشَّهْرَ فَلْیَصُمْه”.
 Kuleini, Muhammad bin Yaqub, al-Kāfī, vol. 1, pg. 266, hadith 4. Daar al-Kutub al-Islamiyyah Press, Tehran, 13656 (solar calendar), 8 volume edition.
 Aal Imran:97 “وَ لِلَّهِ عَلَى النَّاسِ حِجُّ الْبَیْتِ مَنِ اسْتَطاعَ إِلَیْهِ سَبیلاً وَ مَنْ کَفَرَ فَإِنَّ اللَّهَ غَنِیٌّ عَنِ الْعالَمینَ”.
 Ghafir:60 “ادْعُونی أَسْتَجِبْ لَکُمْ إِنَّ الَّذینَ یَسْتَکْبِرُونَ عَنْ عِبادَتی سَیَدْخُلُونَ جَهَنَّمَ داخِرینَ”.
 Nisa:59 “یا أَیُّهَا الَّذینَ آمَنُوا أَطیعُوا اللَّهَ وَ أَطیعُوا الرَّسُولَ وَ أُولِی الْأَمْرِ مِنْکُمْ...”
 al-Kāfī, vol. 2, pg. 158, hadith 4 “الإمام الصادق (ع) ـ لمّا سئل عن أفضل الأعمال: الصلاة لوقتها، و برّ الوالدین، والجهاد فی سبیل الله”.