In science, theory means it's a well-established, comprehensive explanation that relies on a great deal of supporting data collected using the scientific method (observation, testing, etc.). That doesn't mean we know everything about it, as there's always more to learn, but it's not a mere hypothesis. Theory is the very best evidence-based explanation we have. The problem is that everyday use of the word "theory" is more akin to "hypothesis" and that's where young-earth creationists get sidetracked, claiming evolution is "just a theory." They reveal themselves to be incredibly ignorant of the topic, confusing evolution for abiogenesis, conflating evolution with the big bang theory, and making silly statements like, "If we came from monkeys, then how come there are still monkeys?" The relationship of known life forms based on their physical characteristics and the fossil record matches precisely with what genetics tell us about relationships. That alone is significant. The consistent order of fossils in geological layers confirms chronology. Various dating methods confirm the age of the layers and provide us with a solid understanding of gradual change over great spans of time. The fact that multiple scientific disciplines provide consistent results is what makes evolution such a strong theory.

The debate about the theory of evolution was over by about 1870. That some cultists are denying it because it contradicts their religious dogma isn't debate, it's just denial.

The pile-on about your understanding of the word theory was pretty thorough, so I'll address your use of skeptic. A skeptic isn't someone who doubts. He or she is someone who wants his or her beliefs to be supported by evidence. So a skeptic should accept evolution as the explanation for Earth's biodiversity because that is where the evidence leads.

You need to understand what a theory is in science. A theory is a means to explains the facts and give a valid explanation of a phenomenon. It is the highest level of scientific understanding and explanation.

There is no doubt that evolution is established as fact. We know it happens. It has been observed. We know a great deal about how it happens. We can make reasonably accurate predictions based on the theory. The only area open to question is the element of natural selection, the Darwinian posit, however, even that is now pretty well pinned down.

Short, sweet, and enlightening article: [nas.edu]

Evolution is fact.

In science theories are considered facts. The fact that people are still debating about this in the 21st century says a lot about how little some of have "evolved".

You need to educate yourself on what science calls a "theory" versus what you think a "theory" is. In scientific discussions, a theory is NOT a "plausible conjecture".

Evolution is a fact, and documented just as solidly as the theory of gravity. If you think gravity is still a theory, please step out of a 20-story window with a stopwatch, pen and paper and document the results.

People who conjecture about scientific studies and scientific theories should probably get a degree in a hard science like biology, physics, or even mathematics before they start spouting off crap about which they know nothing. Ignorance is almost as ugly as religion.

That does get kind of interesting- there's biological evolution, and then there's Darwinian natural selection. Biological evolution is an observable phenomenon- a fact, if you will. We can observe it happening, be it through modern examples like bacteria becoming resistant to antibiotics or through observing the fossil record. Darwinian natural selection is a theory explaining how evolution works (although, just to muddy things up, some people are starting to consider natural selection an observable phenomenon, too!). So I think that's where part of the confusion comes in. You've got an evolutionary theory (natural selection) that in the public's eyes has become synonomous with biological evolution itself, but in reality, the two things are different.

Evolution ceased being a "theory" a long time ago. Those who insist otherwise are incorrect.

Evolution is a still just a theory, highly supported by evidence and 99.9% likely to be true, but hell maybe a plasmid of extraterrestrial origin carried here by a meteorite caused one if the developmental steps not just plain old natural selection. Not likely but vaguely possible so like everything else that is filtered through our own limited perceptions it is just a theory.
If you want certainty, only religion promises that.

The process of evolution is something which we can study and observe with all of our senses, so it is something which we are able to categorize as fact.

Evolution is a proven scientific principle, not a theory. there things in our current conceptions about evolution which will be proven wrong later. Of course -- that is the nature of the scientific process. But, it still does not negate the principle.

Just my plain and simple answer. Something built us from the beginning.

'Just a theory' is an uneducated and unscientific description of ANY scientific theory. Especially when referring to evolution by natural selection. Not only is there not a single scrap of evidence to the contrary of this theory, but several other fields of study have arisen due to it's discovery, and/or corroborated it's validity.

Maybe you don't quite understand what a scientific theory is .i.e. The theory of gravity , the theory of flight . The theory of relativity. There is no debate

you are so right we humans have cheated nature in so many things, especially our food and not always if at all for the best. nature selects because of changing habitat the strong or adaptable where man does what he likes but the exact same process. that's just a fact.

Evolution is a fact like gravity is a fact. We do not absolutely understand how either one works, but the facts remain.

Scientific theory
A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation. Scientific theories are the most reliable, rigorous, and comprehensive form of scientific knowledge.

and as stehen hawking often says, "a theory can never be proved to be correct."

What a great post to bring out all our scientists in here. Thanks guys for going after this and keeping it alive.

[nas.edu]

This gives a good explanation.

Animals (humans included) adapt to new environments over time. This explains why humans around the world look different (bone structure, features, skin color, and hair).

All hypotheses

I am agnostic and I wish I could say evolution was a matter of fact. Science can trace us from fish, to
amphibians, to land mammals, to primates, but at least I haven't heard that they have found the definitive missing link. I don't have another plausible explanation, but still will struggle saying evolution is fact. In some ways it makes me feel inadequate as an agnostic, but I am true to my self.

It’s a theory but highly supported by evidence.