Ik Onkar (Gurmukhi: ੴ, ਇੱਕ ਓਅੰਕਾਰ; Punjabi pronunciation is the symbol that represents the one supreme realityand is a central tenet of Sikh religious philosophy. Ik Onkar has a prominent position at the head of the Mul Mantar and the opening words of the Sri Guru Granth Sahib. Ik (ਇੱਕ) means one and only one, who cannot be compared or contrasted with any other, Onkar (ਓਅੰਕਾਰ) is the one universal ever flowing divine melody and existential unstruck, never-ending sound of God.
To simplify Ik means one, Oang the creator and Kar means the creation. So, the creator and his creation are not different and He the supreme creator resides everywhere and in everything.