Jagadguru Shankaracharya
गुरुर्ब्रह्मा गुरुर्विष्णुर्गुरुर्देवो महेश्वरः ।
गुरुरेव परं ब्रह्म तस्मै श्रीगुरवे नमः ॥१॥
Gurur-Brahmaa Gurur-Vissnnur-Gururdevo Maheshvarah |
Gurure[-I]va Param Brahma Tasmai Shrii-Gurave Namah ||1||
Meaning: The Guru is Brahma, the Guru is Vishnu, the Guru Deva is Maheswara (Shiva),
The Guru is Verily the Para-Brahman (Supreme Brahman); Salutations to that Guru.
In Hinduism a teacher is considered as worthy of great respect irrespective of the fact whether he is a spiritual teacher or secular teacher. The word ‘Guru’ means “the dispeller of darkness.
A Guru is someone who Removes the Darkness of Ignorance from our Blind (Inner) Eyes 
by applying the Collyrium of the Light of Knowledge. A disciple is someone who approaches his Guru for knowledge and has a lot of ‘shraddha’ (humility) for his Guru. A disciple without shraddha or respect for his Guru can never attain true knowledge. My Guruji says a True Knowledge is always crowned with humility.
Bhagvad Gita also says :-
श्रद्धावान लभते ज्ञानं तत्परः संयतिन्द्रियः ।
ज्ञानं लभत्वा परम् शान्तिं अचिरेण अधि गछति ।।
The man of shraddha, the devoted, the master of his senses obtains knowledge. Having obtained knowledge he promptly goes to the peace Supreme.
Spiritual Guru is considered as someone equivalent to Brahman (Supreme GOD), who knows the nature of Brahman and has realised the Supreme Divine by his Tapas and Sadhana.
Apart from the faith in Guru, a student must also have confidence in himself that when he will be guided by his Guru he will be able to succeed. Not everyone can be a Guru, only a person with an exemplary life and high spiritual attainments can be a Guru.
