According to Lacan's subject theory, the order of the real is everything which resists symbolization and representation in the unconscious. The real according to Lacan is that which resists the dialectical process typical of the symbolic order, in which one signifier is interchangeable with another. The real according to Lacan does not exist as a signifier. Lacan calls this phenomenon, which cannot be symbolized, as the Thing (with a capital T). Lacan's concept of Thing is inspired by Freud's distinction between things which are represented in the unconscious and things that do not.
Since the real for Lacan refers to an existence which cannot be a part of the symbolic order, and therefore cannot be symbolized or conceptualized, it is associated with trauma but also with pleasure, which subverts symbolic bans and aims at achieving the Thing. The real is in a sense pure absence since it is resistant to symbolization. For the same reason the real also lacks nothing.
The real is associated for Lacan with the death drive: the relation between destructive behavior and the obtainment of pleasure. The real is the realm of pure pleasure, which is symbolically castrated by the symbolic order. Lacan essentially talks about two types of subjects, the subject of language and the subject of pleasure, which are not distinct from each other but rather infused.
The need for pleasure is formed according to Lacan at an early state, before language is acquired, and in the context of the initial engagement with the mother which produces satisfaction and frustration at the same time. Following birth, the baby's first and most intimate contact is with the mother, and this is for Lacan as intimate as he is ever going to get with anything. He calls this sensation extimacy.
Extimacy for Lacan is the source or a constant yearning the various forms of imagined unities with ideal "others" (starting from the mother onwards to ideology). The yearning is also for various forms of pleasure which include not only enjoyment but also destruction. This is why the subject cherishes his symptoms and even if he is willing to eventually give it up another one will take its place. Symptom according to Lacan is a creative way to invent excess pleasure in a place which limits pleasure. If identification with the name of the father as a signifier in language has a castrating effect, the symptom allows the subject to reunite the subject with its pleasure. This is why the symptom according to Lacan is not only a subconscious message but also an expression of the real which resists symbolic discipline.