Guru shlokam

Guru means teacher. Of the two syllables Gu Ru.  As scriptures say

guk¡ra ¾ca a¯dhak¡rµ hi ruk¡rast£ja uccyat£

aj²¡na grµsakam brahma guruv£va na sa¯k½aya

गुकार श्च अंधकारो हि रुकारस्तेज उच्च्यते
अज्ञान ग्रोसकम् ब्रह्म गुरुवेव न संक्षय

"Gu" kaara means darkness and "ru" kaara means dispels. The parabrahma who swallows the ignorance is refered to as Guru.  

Guru plays an important role in everybody's life.  For everybody "mother" is the first guru.
 

Gurur Brahma Gurur Vishnuhu Guru Devo Maheswaraha
Gurussakshaat Parabrahma Tasmai Shree Gurave Namaha

गुरुर्ब्रह्मा गुरुर विष्णुहु  गुरु देवो महेश्वरः 
गुरुस्सक्षात परब्रह्म तस्मै श्री गुरवे नमः

Guru, the teacher is considered equivalent to GOD

Guru is Brahma - the Generator or (creator), 
Guru is Vishnu - the Organizer,
Guru is Maheswara - the Destroyer

So
Generator
Organizer
Destroyer
is
GOD
since guru helps in instilling and maintaining knowledge, and destroying or dispelling ignorance, guru is considered as GOD