In Genesis 6:4 we are introduced to the Nephilims for the first time and it says that "The Nephilim were on the earth in those days - and also afterward." Then we had Noah's flood. After that, the Nephilims were mentioned again in Numbers 13:33, where they were living in the land of Canaan.
I thought Noah's flood killed all people and animal that had breath in their nostrils. Why were the Nephilims not killed? In Numbers 13:33 it mentioned that they were the descendants of Anak, if they were descendants of Anak then they were not descendants of Noah and his sons. How does that work since all of the earth was repopulated with Noah's sons?
"There were giants on the earth in those days, and also afterward, when the sons of God came in to the daughters of men and they bore children to them. Those were the mighty men who were of old, men of renown" (Genesis 6:4).
The word "Nephilim," translated as "giants" in the New King James Version, means people who were physically bigger than typical men or who were of outstanding skill (as in "he was a giant among men"). Notice that the giants existed before and after the sons of God married the daughters of men. The giants were not a product of the sons of God marrying the daughters of men. Thus before the flood there was a population of physically large men or very skilled men. The latter probably was what was intended since the passage goes on to say, "Those were the mighty men who were of old, men of renown."
"There we saw the giants (the descendants of Anak came from the giants); and we were like grasshoppers in our own sight, and so we were in their sight" (Numbers 13:33).
Here again the word "Nephilim" is being used and again translated "giants," but here it is definitely referring to physical stature. Anak must have been an exceptionally large man and his descendants were large as well. "Where can we go up? Our brethren have discouraged our hearts, saying, "The people are greater and taller than we; the cities are great and fortified up to heaven; moreover we have seen the sons of the Anakim there"" (Deuteronomy 1:28). They weren't the only nation of large people: "The Emim had dwelt there in times past, a people as great and numerous and tall as the Anakim. They were also regarded as giants, like the Anakim, but the Moabites call them Emim" (Deuteronomy 2:10-11).
Therefore, Nephilim is not a word for a race, but a characteristic of some people that crops up at times in the human race.