Imam Ali (A.S.), the First Compiler of the Holy Qur'an
"...and recite the Qur'an as it ought to be recited." (lit. with Tarteel) - Qur'an 73:4
When asked about the meaning of Tarteel, Imam Ali (AS) has said: "It means that the Qur'an should be recited with tajweed and with due observance to the rules of waqf (pausing or stopping at the end of a verse)."
Tajweed comes from the word 'jawwada' which means 'to do better or improve'. Tajweed means performing, acting or making an effort repeatedly in order to reach the perfect level. In other words 'making beautiful' or 'striving for excellence'.
Huroof (letters) - This is the pronunciation of letters correctly from their makharij (place of origin), with their sifaat (qualities) and the relationship of letters to other letters and words.
Wuqoof (pausing/stopping) - This is the rules of where and how to pause or stop as well as from where and how to resume.