Why they are so important
The Companions learned Islam directly from the Prophet ﷺ, lived by it and faithfully passed it on to the following generations. They memorised and wrote down the Qurʾān and transmitted the words and deeds of the Prophet ﷺ.
Allah praised them in the Qurʾān, and the Prophet ﷺ called their generation the best.
رَّضِيَ ٱللَّهُ عَنۡهُمۡ وَرَضُواْ عَنۡهُ
… Allah is pleased with them, and they are pleased with Him …
The Prophet ﷺ said: "The best of people are my generation, then those who follow them, then those who follow them."
Ṣaḥīḥ al-Bukhārī 2652