The Arabic word "Hadith" literally means "statement" or "talk".
In the Shari'ah, the word Hadith means those things or action, which Rasulullah SAW said, did or approved.
Sometimes the word "Sunnah" is also used for Hadith, but usually "Sunnah" is used to report a deed or actions while Hadith is used for "talk".
Some basic common terminologies used in Hadith are as follows:
1. Athar - That statement or act which is attributed to the Sahabah RA.
2. Sanad - A group or chain of narrators who narrates a Hadith from Rasulullah SAW.
3. Mutan - The actual textual content of the Hadith.
4. Rawy - The narrator of the Hadith.
5. Marwy - Same as Mutan i.e. the actual textual content of the Hadith.
6. Hadith Qudsi - A Hadith which Rasulullah SAW quotes from Allah Ta'ala, which is not in the Qur'an.
7. Marfu' Hadith - A Hadith which is traced back to Rasulullah SAW directly.
8. Mau'quf Hadith - A Hadith of which its chain stops at Sahabah, and not Rasulullah SAW.
9. Maqtu' Hadith - That statement which is attributed to some Tabi'een RA.
10. Mutasil Hadith - That Hadith which has successive narrators, and there are no gaps or omission in the chain.
11. Musnad Hadith - That Marfu' Hadith which the chain is Mutasil i.e. no gaps or omission in the chain.
THE TYPES OF HADITH
Hadith has five types:
1. Mutawatir - That Hadith where there is a group or a large number of narrators, that it is impossible for them to agree to tell a lie.
2. Khabr Wahid - That Hadith which does not reach the status of Mutawatir.
3. Mashur Hadith - That Hadith which is handed down by at least three or more narrators and does not reach the state of Mutawatir.
4. Aziz Hadith - That Hadith which is handed down by at least two or more narrators.
5. Ghureeb Hadith - That Hadith which is handed down by only one narrator.
THE WELL-KNOWN AUTHENTIC COLLECTIONS OF HADITH
1. Sahih Bukhari.
2. Sahih Muslim
3. Sunan Abu Dawud
4. Sunan Nasa'i
5. Sunan Tirmidhi
6. Sunan Ibn Majah
7. Muwatta Imam Malik
THE SIGNIFICANCE OF HADITH
There are people nowadays who incorrectly say that you do not need Hadith, and that Qur'an is enough for guidance to the straight path.
The correct view and understanding is that many times the Qur'an gives us the general principal of an order; but to understand the order clearly in its fullest sense - Hadith is required.
For example - A teacher, whenever he is preparing for that class or "Sabak" which he is going to teach tomorrow. He will look into many number of “Sharahs” to get a very clear and comprehensive view.
So similarly, the Qur'an tells us the principle, but to get a comprehensive view we will need Hadith.