A population is essentially just a collection of all living things in one category. People are one population, insects are another, etc. Communities are "more organized" populations. Soccer players hang out with soccer players, spiders hang out with spiders. We split into "our people" within our population.
I know that may be a little confusing, but if you have anymore questions feel free to ask. I hope I was able to help. Best of luck!
Answer:
Matution include changes as small as the substitution of a single DNA building block, nucleotide base, with another nucleotide base.... Other matutions result in abnormal protein product.