Faith Is

Now faith is the substance of things hoped for, the evidence of things not seen. Hebrews 11:1

Based on Hebrews 11:1-7

Faith is the means to make use of things that we want but do not have.
Faith is the conclusive evidence for things that we cannot possibly see.
We know this because
By faith people of old were able to be declared good:
By faith we know about the way God made everything from nothing, and that things have not evolved from other things.
By faith Abel chose to obey God in details unlike Cain, this was evidence that Abel was right with God.
By faith Enoch never died, but went to be with God because Enoch pleased God. Enoch needed to believe certain things about God to please him, including that God was real and that God does reveal himself those that are trying to get to know him.
By faith Noah built a giant boat to save his family from a flood that had never been experienced before and there was no evidence for previously. Noah feared that this flood would occur only because God gave him his word it would. The others in the world at the time chose not to believe God's word through Noah, but determined to survive without God's help. Those who did not have faith were not right with God and were lost; those who did have faith were right with God and were saved.