(This is) a clarification of the categories of Tawheed, and they are three:
Tawheed ar-Ruboobiyyah (Lordship)
Tawheed al-Uloohiyyah (Worship)
and Tawheed al-Asma’ was-Sifaat (Names and Attributes)
As for Tawheed ar-Ruboobiyyah: Then it is to believe that Allaah, the Most High, is the Creator of everything, and is the Disposer of Affairs of everything, and He has no partners besides Him in that.
And as for Tawheed al-Uloohiyyah: Then it is to believe that Allaah, the Most High, is the One worshipped in truth, and He has no partners besides Him in that. And this is the meaning of Laa Ilaaha Illa Allaah, and the meaning of this is: there is no deity worshipped in truth except Allaah. So all the acts of worship from Salaah (prayer), Sawm (fasting), and other than them, then they must be (done) sincerely for Allaah alone and it is not permissible to associate, anything from these acts of worship, with anyone other than Allaah.
And as for Tawheed al-Asma’ was-Sifaat: Then it is to believe in everything that has been revealed in the Noble Qur’aan and the authentic ahadeeth, from the names of Allaah and His attributes. And affirming them for Allaah alone, at the level that is befitting the Most High, without Tahreef (perverting the texts), without Ta’teel (denying their meanings), without Takyeef (seeking after their specific details), and without Tamtheel (likening Allaah to His Creation). Complying with the statement of the Most High:
“Say (O Muhammad): “He is Allaah, (the) One. Allaah-us-Samad (The Self-Sufficient Master, Whom all creatures need, He neither eats nor drinks). He begets not, nor was He begotten; And there is none co-equal or comparable unto Him.” – Al-Ikhlas (112):1-4
And His (‘Azza Wa Jall) statement: “There is nothing like unto Him, and He is the All-Hearer, the All-Seer.” – Ash-Shura (42):11
Shaykh ‘Abdul ‘Azeez bin ‘Abdullaah bin Baaz (Rahimahullaah)
Taken from: Duroosul Muhimmah Li ‘Aamatil Ummah