Is is legal to photograph a model nude and sell her photos online if I have her consent to do so?

Depends on the law where you are. In Britain it would be legal provided she is over 18 and has given written consent for the use to which you intend to put those photos.

WRITTEN consent. And no pictures of someone under the age of 18.

You don't need to be an attorney in such matters and you don't need to be a genius on such matters; all you need is common sense and reasonable understanding of what is or isn't allowed where you live. Speak with those who are in business and ask them to help you understand things; most will comply.

A lot depends on a few details you neglected to include. For example, the age factor. IF you're a minor, you cannot legally participate in any business negotiations, contract-signing and certainly not engage in commercial enterprise. Also, is the model of legal age? You can be be charged with a slew of charges if you photograph a minor in the nude... even if YOU are also a minor, but worse if you're of legal age. Of course, laws vary from state to state and from country to country, so you'd have to consult with local laws at wherever place you live in.

Now, here's where it's going to take an adult, mature mentality: you need to be well aware of what constitutes a photo of a nude model and what is pornography; I will not engage in semantics here nor won't entertain absurd, asinine, ludicrous, puerile questions pertaining to semantics or definitions. Either you know or risk getting in difficulties by feigning ignorance (be aware that different states within many countries will remind you "ignorance is no excuse").

I have NO idea what your background is in photography; but judging by your question, you must be very young and inexperienced, you may even be another guy with a camera who discovered where the shutter release button is, and you think you'll be carting off mounds of money in a wheelbarrow as fast as you can. You're in for a huge disappointment. There are hundreds of thousands like you also thinking the same thing. Too bad you aren't interested in the ART of photography as much as you are delusional about making money. Your very question is one asked by many, many newbies, which is why I said the foregoing.

I'm not a photography expert about the consent part. I'll touch on your comment about "what is pornography?". I'm not expert about that either...... But the question the laws have asked in the past amount to "is it prurient?" Prurient is an archaic word that basically means nasty or overtly sexual. So if it's just a girl without any clothes on it might actually be considered innocent. If the picture says, "hey come and get it" then you might have some problems.

If you have written consent, you don't have a problem with the model and she is of age with respect to signing a contract. However, if you live in a country where pictures of naked women are illegal, then you could get into trouble.

In the US , you need to have a signed and dated contract . It has to state how the photos will be used .

Without a contract , you can be sued .

Yes if you have a signed release to that effect.

If you have a WRITTEN AND SIGNED model release, it is legal. Without a SIGNED release, you are potentially liable.

HINT: have a WITNESS sign the release as well.

In some countries it is legal if you have model's permission but in some countries its illeagal

Yeah, why not..