Tauheed is the basic fundamental of Islam and anyone who want to be called as Muslim must believe in Tauheed. There are three categories of Taheed.
Almighty Allah is the sole creator of Everything. No one is partner with Him. Everything happen by the will of Allah
Refer to Allah as He referred to Himself without giving Him new names or attributes.
Worshiping no one except Almighty Allah. Submitting yourself to Him and seek mercy and help From only and solely Allah.