Upon surviving the flood unscathed, the first thing Noah does is worship by offering "burnt offerings" to God (Gen. 8:20). This offering is one in which the animal was totally consumed in the fire. The Hebrew word means "to go up" because the entire offering goes up in smoke.
The whole burnt offering represented the individual's total surrender and dedication to God. In response, God "smelled the pleasing aroma" (Gen. 8:21) representing his acceptance.