|This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, or tell me)|
Semiotics is, roughly, the study of signs and how we relate them to meaning.
It's a wide concept including
- signs (something that can be interpreted to have a meaning),
- sign processes (semiosis) (any process/activity that involves signs, and probably meaning),
- ..etc, like likeness, analogy, allegory, metonymy, metaphor, symbolism, signification, and communication.
Linguistics is mostly about intentional meaning.
You could say that semiology is more about the signs and symbols and more anthropological, while linguistics more about the structure, meaning and meaningful communication.
As such, linguistics courses may skim over semiology, or use the term only for all the inbetweens - analogy, allegory, metonymy, metaphor, symbolism, and also conduct, behaviour, and a lot of other sociology.
It also overlaps with philosophy, relating to structuralism, and more. (see e.g. Saussure)
Entirely unintentional signs include e.g. diagnosis, as a symptom can be a a sign of a medical condition.