Tajweed is the rules of the proper recitation of the Quran. The word Tajweed is derived from the Arabic word ‘Jayyid’ which means good. So Tajweed means to make ones recitation good and beautiful while adhering to the correct rules.
Tajweed is amongst the branches of knowledge that every Muslim is required to give due care and have knowledge of. This is because this branch of knowledge is linked to an act of worship that is fardu ‘ayn (obligatory) on each and every Muslim and that is reciting the glorious Quran.
Reciting the Quran is to be done in a specific way and has a specific description that was reported to us through a chain from our teachers, to their teachers and their teachers all the way to the The Prophet (saws) who learned it from Jibriil (as) and Jibriil (as) heard it from Allah (swt).
This is the meaning behind the famous line of poetry by Imam Jazari when he said:
لأَنَّــهُ بِـــهِ الإِلَـــهُ أَنْـــزَلاَ وَهَـكَـذَا مِـنْـهُ إِلَـيْـنَـا وَصَـــلاَ
Because this (Qur’an) was revealed to us by Allah in this form
And exactly like this (with tajweed) it reached us (from our Prophet, then related in authentic chains over generations to our present day shuyookh and those with ijaazah).
Tajweed or the the proper pronouncement of the Quran is taken from the language of the Arabs because the Quran was sent down in their language, so the Quran is Arabic in terms of both words and meaning and even the dialect.
The different Arab tribes used to have different dialects in the way they would pronounce different letters but the Quran was sent down in the dialect of the most eloquent tribe which was Quraysh. And the Quran was recited by the most eloquent amongst the Arabs and that is the Prophet Muhammad (saws).
So when we read the Quran with Tajweed we are pronouncing the Quran according to the most eloquent Arabic dialect, for we are following the dialect of the Prophet (saws) and his pronouncement and whatever he taught of the recitation to the Sahaba such as Ubay ibn Ka’ab, Abdullah ibn Mas’uud, Zayd ibn Thaabit and other than them amongst the Quraa (recitors) of the Sahaba may Allah be pleased with them all.
The scholars of Islam gave this branch of knowledge known as Tajweed great care and authored regarding it countless books and countless lines of poetry to make it easier for the people.
Amongst the greatest of the scholars who authored and established this great knowledge is Abu ‘amr addaani, Makee ibn abi taalib al-qaysi, As-shaatiby and Al-Jazari. These scholars rahimahumullaah are the leaders in terms of memorisation and it terms of teaching the recitation of the Quran. They are the imaams of this branch of knowledge called Tajweed, so the recitors of the Quran up until the end of time are dependent on their works.