All Hindu deities represent cosmic energies that are part of the Divine Universal Energy or the Supreme God-head. In this regard, Ganesh represents the energy that is capable of removing obstacles and obstructions. Due to this, he is revered and paid obeisance before starting any auspicious or important work. His blessings are sought before starting travel to ensure safe, smooth journey and successful completion of work.
According to mythology, Ganesh is the second son of the deities- Shiva and Parvati. Here the concept of ‘son’ is used to indicate the product or an effective outcome.
Shiva represents the Male Cosmic energy principle of our form-created world and Parvati (who is another representation of Shakti), is the Female Cosmic energy principle. Both these primal Male and Female cosmic energy principles are responsible for creating our form world.
The energy of this action of creation (kinetic or action energy) is their first son- Karthikeya. Thus Shiva and Shakti together create this form-world as we know.
Their second son is Ganesh. Thus his energy is of prime importance in this created (manifested) world and he is considered as a ruling-leader of the masses. It is due to this leadership position that Ganesh is revered before starting any important task. He is considered as the prime energy of importance in our material world for special occasions as well as day to day existence.