Qualites of a good friend

For qualities of a good friend we have:
Firstly, they always understand each other.
Without talking, just look at each other and understand what the other side thinks, that enough.
Secondly, they always support each other. In some field, no one of all is successful but in sadness, they really need someone by their side.
Finally, they always correct each other's mistakes. Nobody is perfect so it's necessary to improve themselves
In life, we have many friends, but finding a good friend is difficult, if we find a good friend whose qualities, we're really lucky