What it usually means
Most dream images lean one way. The snake does not. It is the animal that kills without limbs and the animal that sheds its skin and continues, and both readings are ancient, widespread, and equally well attested. A snake appearing in a dream is therefore not yet information. What the snake does is the information.
The common thread under both readings is that a snake is not negotiable. It does not respond to persuasion, it does not care about your intentions, and it moves on its own logic. Dreams reach for it when something in life has that quality — an instinct you cannot argue with, a person who does not operate by your rules, a process already underway that you can only respond to.
It is also the animal people most often over-read. Centuries of moral storytelling have loaded the snake with guilt and temptation, and that layer is real in the culture but is not automatically in your dream. If the snake in your dream did nothing threatening, the dream was not describing a threat.
What changes the meaning
A coiled snake that does not move. Potential, held. Something present and inactive. These dreams often accompany situations you are aware of and have chosen not to disturb.
A snake moving toward you. The situation is no longer static. Not necessarily an attack — attention is the point, and the dream has turned it on you.
Being bitten. The sharpest form, and worth asking where. A bite delivers something into the body; these dreams often follow a piece of news or a remark that got in past your defences and started working.
Holding a snake without fear. A strong image and much more common than people expect. Contact with something dangerous on terms that hold. Often arrives when someone has started handling an instinct — anger, desire, ambition — rather than suppressing it.
A snake shedding its skin. The renewal reading in its plainest form. Something being outgrown, with the old surface still lying there.
A snake in the house. Location is the message. The house is usually the self or the family; something instinctive has got into a place meant to be ordered and safe.
Many snakes. Rarely about snakes at all. Usually the texture of a period that has too many live things in it at once.
Killing the snake. Resolution, or refusal. Both readings are open, and the feeling on waking generally settles which — relief or a small unaccountable regret.
When it keeps coming back
A returning snake tends to track something in life that keeps being noticed and not addressed. The image is persistent because the thing is persistent.
Watch whether the snake changes. If it grows, the dream is reporting escalation. If it stays the same size across months, the subject is more likely your relationship to it than the thing itself. And if a long-running snake dream ends with the snake simply leaving, something usually did get settled in waking life around then — it is worth working out what.
For people with a genuine fear of snakes the ordinary explanation deserves first place. A frightening animal in a dream may be doing nothing more than being a frightening animal.
In Jungian terms
Jung placed the snake among the oldest images the psyche produces, and read it as instinct in a form that consciousness has not domesticated — the part of a person that operates below decision, older than argument.
The ambivalence is the point rather than a problem to be solved. Instinct is what endangers and what renews, and the same energy does both depending on whether it is met or ignored. This is why the snake sheds its skin in so many traditions: the animal that carries the danger is also the animal that models continuing through change.
The practical version is uncomfortable but small. A snake dream asks which instinct you have been treating as an enemy, and what it would cost to look at it directly instead.