What are the criteria for judging a Hadith as authentic (sahih) or weak (da'if)?

The ruling on a Hadith as authentic or weak passes through two stages: the first is collecting and distinguishing the chains of narration (Isnad), and the second is a detailed study of the Isnad and the text (Matn). For those who are not specialists, one can refer to certain guidelines, including: if the Hadith is in Sahih al-Bukhari, Sahih Muslim, or Muwatta Malik, then it is authentic. Also, if the Imams have ruled it authentic or weak and no one else has contradicted them, or if the rulings of scholars have converged on it, then it is as they said. Furthermore, a Hadith is considered weak if it discusses matters for which no authentic Hadith exists, or if certain books, such as "Al-Du'afa' al-Kabir" by Al-Uqayli, are unique in transmitting it.