How to decide the authenticity of a hadeeth?

Usool hadith teaches the science of dealing with hadith and gives important knowledge that will help us determine which hadith is authentic (sahih) and which one is weak (dhaeef).

A hadith mainly consists of two parts: Sanad (chain of narration) and Matn ( the text) and the authenticity of a hadith or its weakness is linked to these two.[1]

Reference:

[1] Dr M Tahhan: Taysir Mustalah Hadeeth: p. 43