One of the six most authentic collections of the Ahadith (Sahih al-Bukhari, Sahih Muslim, Sahih al-Tirmidhi, Sunan Ibn Majah, Sunan Abu Dawud, and Sahih al-Nisa’i) It has 4800 Hadith (selected from a mass of 50,000) divided into many different subjects, each Section containing many Hadith. The numbering system used by Abu-Dawud is consecutive and uninterrupted for the entire collection
Abu Dawood, Sulaiman bin Al-Ash’ath bin Ishaq Al-Azdi As-Sijistani, who was one of the eminent Imam of Hadeeth, was born in 202H. He studied Hadeeth under Imam Ahmad bin Hanbal along with Al-Bukhari and taught many of the later scholars of Hadeeth, like At-Tirmidhi and An-Nasaa’ee.
Abu-Dawud lived a couple of centuries after the Prophet’s death and worked extremely hard to collect his ahadith. Each report in his collection was checked for compatibility with the Qur’an, and the veracity of the chain of reporters had to be painstakingly established. Abu-Dawud’s collection is recognized by the overwhelming majority of the Muslim world to be one of the most authentic collections of the Sunnah of the Prophet (pbuh), however it is also known to contain some weak ahadith (some of which he pointed out, others which he did not).
Though Abu Dawood collected 50,000 Hadeeth, he compiled 4,800 Hadeeth only in his book entitled As-Sunan, which he taught in Baghdad and other major cities at that time. He died at Basra on Friday in the month of Shawwal 275 H. Sunan Abu Dawood has been translated to English.
He was one of the most widely travelled of the scholars of ahadith, going to Hijaz (Saudi Arabia), Iraq, Khurasahn, Egypt, Syria, Nishapur, Marv, and other places for the sole purpose of collecting ahadith. His primary interest was in law, hence his collection focuses purely on legal ahadith. From about 50,000 ahadith, he chose 4,800 for inclusion in his work based on their superior authenticity.
Source: PDFs and information taken from kalamUllah.com