The eight words
The best-known summary of Wiccan ethics is: "An it harm none, do what ye will." In modern English that's roughly: if it harms nobody, do as you wish. "An" is an old word for "if", and "rede" simply means advice or counsel: not law, not commandment.
Where the wording comes from
The eight-word Rede is publicly documented in connection with Doreen Valiente, who quoted it in a speech in 1964. It belongs to the development of modern Wicca in twentieth-century Britain rather than to any documented ancient tradition. Its phrasing echoes older occult and literary material, including Aleister Crowley's "Do what thou wilt", and that resemblance is much discussed.
The longer poems are a separate thing
You'll also meet long rhyming versions: the twenty-six or so couplets often called the Rede of the Wiccae, published in the 1970s. These are not the same as the eight-word Rede, and claims that they were handed down from a much earlier date are disputed and not established by evidence.
So what counts as harm?
Living without causing any harm at all is probably impossible: you eat, you take up space, you sometimes have to disappoint people. Many Wiccans read the Rede as a call to weigh consequences rather than as a purity test. Some include harm to yourself; others focus outward. Some apply it strictly to magical work only; others to everything. There is no ruling body to settle it.
The Threefold Law
Also called the Rule of Three: the idea that what you send out returns to you three times over. Some Wiccans hold it seriously as a spiritual principle, some treat it as a vivid teaching image, and others regard it as a later moralising addition they don't accept. It is a belief within some traditions, not a demonstrated fact about the world.
Consent
The widely shared convention is that you don't work on someone without their agreement. That covers work aimed at making a named person love you, want you, or change their behaviour, and, less obviously, healing work sent to someone who hasn't asked for it. Reframing towards yourself is almost always available: your clarity, your boundaries, your capacity to have the conversation.
Consequences, thought through
Before any working involving another person, four questions do most of the work. Who is affected, including people you haven't considered? What outcome do you actually want, stated plainly? Is there a less coercive framing that gets you there? And what would you think if someone did this to you?
Do the ordinary thing first
Magic is not a substitute for medical treatment, mental-health care, legal advice, safeguarding, the emergency services, or a difficult conversation. Alongside is a personal choice. Instead of is where people get hurt, and it is where beginners are most often misled.
Health and healing claims
Never tell anyone, including yourself, that a magical or herbal practice will treat, cure or replace medical care. This matters most when someone is frightened and looking for hope. It is also the single most common way this subject does real damage.
Environmental responsibility
A nature-centred religion that leaves a mess is embarrassing. Don't leave non-biodegradable offerings outdoors, don't put salt on soil or in ponds, don't float things in waterways, take cuttings sparingly and never from protected or scarce plants, and check local rules before lighting anything outside.
Cultures and closed practices
Some practices belong to specific living communities and are restricted to initiates or members: that's what 'closed' means. Where a tradition's own practitioners describe something as closed, that's the answer. If you're drawn to material from a culture that isn't yours, read what its own practitioners have written before adopting anything, and be honest about where things came from. There is a fuller lesson on this in Going Deeper.
Exploitation and red flags
Warning signs, in teachers, groups and online sellers alike: fees that escalate, especially to remove a curse they have just told you about; sexual pressure of any kind; isolation from friends, family or other groups; secrecy used to prevent you discussing someone's conduct; leaders who cannot be questioned; and 'only we are real Wiccans'. You never owe anyone an explanation for leaving.
Nobody absolves you
There's no confession, no clergy with authority over your conscience, and no salvation model. Ethics in Wicca get worked out by the practitioner, which is either liberating or slightly terrifying, depending on the day.