What is the definition of Tawhid linguistically and terminologically?

Linguistically, Tawhid means making something one, and it is only achieved through negation and affirmation: "There is no god but Allah." Technically, it is singling out Allah in what is exclusive to Him concerning Lordship (Rububiyah), Divinity (Uluhiyyah), and Names and Attributes (Asma wa Sifat). Tawhid is divided into three categories:

1. Tawhid al-Rububiyah (Oneness of Lordship): Singling out Allah in His actions, such as believing that He alone is the Creator, Owner, and Disposer of affairs. Allah Almighty says: (Allah is the Creator of all things, and He is over all things a Trustee).

2. Tawhid al-Uluhiyyah (Oneness of Divinity): Singling out Allah in the actions of His servants, meaning that servants direct their actions of worship solely to Allah. Allah Almighty says: (So whoever would hope for the meeting with his Lord - let him do righteous work and not associate anyone with the worship of his Lord).

3. Tawhid al-Asma wa al-Sifat (Oneness of Names and Attributes): Affirming what Allah has affirmed for Himself or what His Messenger (peace be upon him) has affirmed for Him, without distortion (Ta'wil), alteration (Tahreef), resemblance (Tamtheel), how-ness (Takyeef), or negation (Ta'teel), based on Allah Almighty's saying: (There is nothing like unto Him, and He is the All-Hearing, the All-Seeing). This Tawhid is what Allah sent the messengers with, to lead people from darkness into light.