The preliminary Tajweed:

The articulation points of the letters:
Point of articulation The points of articulation and its letters
1 Al jaouf (empty space in the mouth and throat): includes the three long vowels The long vowel: (ا) The long vowel : (و) The long vowel : (ي)
2 Al halq (throat): includes three points of articulation The bottom (deepest part) of the throat includes the letters (ه-ء) The middle of the throat includes the letters (ح-ع) The closest part of the throat, includes the letters (خ-ع)
3 Al lisan (The Tongue): includes 10 points of articulation for 18 letters ⦁ قَ ⦁ كَ ⦁ جَ شَ يَ
⦁ ضَ ⦁ لَ ⦁ نَ
⦁ رَ ⦁ طَ دَ تَ ⦁ صَ سَ زَ
⦁ ظَ ذَ
4 Al khaichoum (the nasal passage – Nose) includes the nasling that accompanies the letters (م-ن)
5 Ash-shafatan ( The two lips) ⦁ فَ ⦁ مَ بَ وَ غَيْرُ
Distinctive features of letters
The letters have two qualities: Permanent (necessary) and Temporary.
1 – Necessary qualities:
Is the trait that accompanies the letter and does not cease with it in any way such as (Jahr-Itbaaq-Isti’laa).

Temporary qualities:
This quality is inconsistent with the letter in some cases, and it is disobeyed in other cases according to his position in the speech such as (Assmilation “Idgham” –Izhar- Ikhfaa’-Madd- …..).

– We are now talking about necessary traits (having no opposites) and scientists have been divided into two features: letters with distinctive opposing features and letters with distinctive features having no opposites.
Note :
The necessary traits (having no opposites) must accompany the letter in all its cases (conditions) as the letter that bears (have on) (فتحه-ضمه-كسره) and intensity (التشديد) but the case of Soukoun (السكون) is the clearest for clarity articulation points (pronunciation) and the traits.
If we want to pronounce clearly, we put the letter in the case of Soukoun (السكون) and then we add the letter (ء) before that and then read it.
Exemples : اَءْ – اَبْ – اَتْ …………..وهكذا
Letters with opposite distinctive features:
1- الهمس
Murmur (Hams) is airflow of pronunciation accompanying the following letters: (ف-ح-ث-ه-ش-خ-ص-س-ك-ت)
Murmur appears in the case of (soukoun)
Examples: اف – اح – اث

Murmur (Hams) comes in both letters (ك-ت) at the end only because the two letters are loud and the intensity (الشده) comes on both letters before the Hams (اك – ات).

2- الجهر
High voice (الجهر) is stopping the flow of air when pronouncing the letter. The letters are 19 :
(ع ظ–م-و-ز-ن-ط-ا-ل-ب-غ-ض-ذ-ي-ط-ل-ب-ج-د).

3- الشدة
Linguistic: (strong) Intensity.
The stop of the flow of the sound during the pronunciation of the 8 following letters (أ-ج-د-ق-ط-ب-ك-ت).
The sound stops because it is based on his (makhraj) pronunciation.
Intensity has pronunciation difficulties of letter (ب) so we can calm with the murmur (الهمس) for example in the two letters (ك-ت).
4-توسط الصوت
Linguistic : Moderation, it is the moderation of the voice while speaking and also called (البينية) Al baynya. It’s time of pronunciation is longer than (الشده) and less than the time (الرخاوة).
Examples: (ل-ن-ع-م-ر).

5- الرخاوة
Linguistic sense: Flexibility.
This is the flow of sound when pronouncing the remaining 16 letters: (ف-ح-ث-ه-ش-خ-ص-س-ي-غ-ز-و-ذ-ا-ض-ظ).
Flexibility is opposite to intensity (الشده)
The sound of the letter is therefore longer for (الرخاوة) shorter for (البينيه) and cut for (الشدة).