Short answer
Ibadah is everything Allah loves and is pleased with, done for His sake: the rites like prayer, fasting and dua, and also ordinary acts like work, kindness and even sleep when done with a good intention. Worship is owed to Allah alone, and it is the reason He created jinn and humans (51:56).
The fard and wajib acts must be done; ordinary permitted (mubah) acts become rewarded worship with a sound intention. Directing any act of worship, such as prostration, sacrifice or dua for what only Allah can give, to anyone other than Allah is shirk.
The four schools agree on this.
Explanation
The word ibadah comes from 'abd, a servant. To worship Allah is to live as His servant, with love, humility and obedience. "And I did not create the jinn and mankind except to worship Me" (51:56). See The purpose of life in Islam.
Scholars describe two kinds:
- Specific rites, such as salah, fasting, zakah, Hajj, dua and dhikr. Their form is fixed by the Sunnah, so you do them as taught and do not invent new ones.
- General worship: any permitted act done for Allah. Earning to feed your family, smiling at someone, learning, and even intimacy with your spouse. The Prophet ﷺ said that in a man's relations with his wife there is charity.
What turns an ordinary act into worship is the intention. "Actions are only by intentions" is one of the foundations of Hanafi fiqh. The Quran puts it all together: "Indeed, my prayer, my rites of sacrifice, my living and my dying are for Allah, Lord of the worlds" (6:162).
Two conditions make worship acceptable: sincerity, doing it for Allah and not for people, and following the way of the Prophet ﷺ. Doing it to be seen spoils it (see is showing off shirk?), and inventing new rites is bid'ah (see what is bid'ah?).
The Prophet ﷺ said Allah's right over His servants is that they worship Him and associate nothing with Him. That is tawheed in practice. Read Tawheed, shirk and kufr.
The evidence
Quran, Surah Adh-Dhaariyat 51:56
وَمَا خَلَقْتُ ٱلْجِنَّ وَٱلْإِنسَ إِلَّا لِيَعْبُدُونِ ﴿٥٦﴾
And I did not create the jinn and mankind except to worship Me.
Worship is the purpose of creation.
Quran, Surah Al-An'aam 6:162
قُلْ إِنَّ صَلَاتِى وَنُسُكِى وَمَحْيَاىَ وَمَمَاتِى لِلَّهِ رَبِّ ٱلْعَٰلَمِينَ ﴿١٦٢﴾
Say, "Indeed, my prayer, my rites of sacrifice, my living and my dying are for Allah, Lord of the worlds.
All of life can be devoted to Allah.
Sahih al-Bukhari 1
Sahih... إنما الأعمال بالنيات وإنما لكل امرئ ما نوى ...
"Actions are only by intentions, and each person gets what he intended."
Intention turns ordinary acts into worship.
Sahih Muslim 1006
Sahih... وفي بضع أحدكم صدقة ...
"And in a man's relations with his wife there is charity."
Even a permitted pleasure becomes rewarded with the right intention.
Sahih al-Bukhari 2856
Sahih... حق الله على العباد أن يعبدوه ولا يشركوا به شيئا ...
"Allah's right over His servants is that they worship Him and associate nothing with Him."
Worship belongs to Allah alone.
Where the ruling is recorded
- al-Ashbah wa al-Naza'ir (Ibn Nujaym), The first rule: no reward except by intention. A Hanafi statement that permitted acts earn reward only through intention.
- al-Fiqh al-Akbar (Imam Abu Hanifa), Opening section on tawhid. Affirms that Allah alone is worshipped, with no partner.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.