Self injury (SI) is described as “an act which involves deliberately inflicting pain and/or injury to one’s own body, but without suicidal intent.”  Another definition, from the Christian psychologist Dr Kate Middleton states that self injury is: “acting to deliberately injure yourself physically in an attempt to cope with, express or reduce intense or overwhelming emotions.” 
Self injury used to be seen as a desire to commit suicide. It used to be thought that it was leading up to suicide, that it was an attempt, that it was a trial run for an actual suicide attempt. This is no longer seen to be the case. Most self injurers, though they may feel suicidal at times, do not see the self injury itself as a suicide attempt. I, for example, was frequently self injuring at one time, and also felt suicidal, but when I attempted suicide I did not do so by cutting my wrists, as I did with self injury. To me, and to many self injurers, it is a means to stay alive, something that releases the pressure to commit suicide.
The way people hurt themselves depends largely on what is available to them, and whether or not they are in their usual environment. The most common type of self injury is that of cutting or burning the skin, using razor blades, knives, cigarettes or lighters. The arm is a popular place – most of my scars are on my left arm, for example, but legs, shoulders, stomach area, breasts and genitals are also used. Generally the area injured is covered up, although some people may harm on visible areas such as the face and hands, and healed scars may also be uncovered. I personally generally wear short-sleeved tops, even though I have visible scars.
Other types of injury may be pulling out hair, known as trichotillomania and considered separately to “general” self injury; bruising oneself, breaking bones, scratching and wound interference, and overdosing/ingesting poisons.
Self Injury -like
There are, of course, other behaviours which injure the body but which are not defined as “self injury”. Some body enhancements such as cosmetic surgery change and alter the body in a permanent way but are not, in general, described as self injury. The difference, of course, is really that they are inflicted by another, and that they are socially accepted. Some feminist authors describe as self mutilation things like eyebrow tweezing, hair waxing, high heel wearing and corsets. They point out that for a woman today to tweeze the front of her head hair would be described as self injury, but for a woman a few hundred years ago this would have been normal. They challenge our understanding of what self injury is, and make the valid point that all that changes whether you are called a self injurer and given psychiatric treatment, or considered normal and left to get on with life, is whether your actions are socially acceptable. For more information on this an author called Sheila Jeffreys would be useful to you.
Other forms of body enhancement, like tattoos and piercings, and other body modifications, are not generally descibed as self injury because the end result, the tattoo or the piercing, is what the person wants, whereas the mechanism of getting that result, the pain, needles, etc, is something to be endured in order to get the outcome they want. I will be writing further about tattoos/etc as a means of self injury, as it is for some, in another post.
There are some self destructive behaviours which can seem similar to self injury, such as eating disorders, alcohol abuse and sexual risk taking which may be co-morbid with self injury, or not at all, but the difference with these behaviours is that they are essentially normal behaviour gone out of control, and do not face the social stigma, the abnormality of self injury in our culture.
Marginally self injurous behaviours are things like overworking, fighting and dangerous sports. Here the aim can be excitement, competition or achievement, whereas self injurers typically look for release of emotion, comfort, and/or a remit from disassociation. More like self injury are things like smoking, which can be used as a comfort and to help cope with distressing situations, or when fighting is an attempt to distract from our feelings.
Babiker and Arnold (see references) suggest that at the heart of self injury is self-hatred. If your activity, no matter how dangerous, is not motivated by self hatred, then it is not self injury.
Types and Sub-types
Armando Favazza wrote a seminal book about self injury called “Bodies Under Seige: Self-mutilation and Body Modification in Culture and Psychiatry” (Baltimore: The Johns Hopkins University Press, 2nd Ed, 1996). This book set out much about self injury, and was the first real work about it. Favazza wrote more widely about self injury than most authors do now, and included several types of self injury which are considerably more rare and which do not generally get mentioned. He described two types of self mutilation: culturally sanctioned (such as certain ancient rituals still practised by some today), and deviant self mutilation. In this section he further identified three sub-types: major self mutilation (such as the removal of an eye, the testicles, etc) which was mostly associated with psychosis; stereotypic self mutilation (for example, repetitive banging of the head) often found in intellectually disadvantaged people and those with autism, among other things; and moderate/superficial self mutilation. In this last category he placed the self injurer as we know them.
The other types of self injury are less common (or less visible to us) but it is important to remember them. It is interesting to note that many who remove an eye or a hand, for example, believe they are following Jesus’ command in Matthew 8:18-19. However, I shall not be focussing on major or stereotypic self injury as my aim in this piece is to discuss “standard” self injury.
To conclude: self injury is the deliberate injury or alteration of the body, without suicidal intent. There are other ways in which we injure our bodies, but they are either not a direct harm (e.g. smoking, where we do not see the damage at the time) or come from a different mental state to self injury.
 Babiker, G & Arnold, L, “The Language of Injury: Comprehending Self-Mutilation” (Leicester: BPS Books, 1997) p2
 Middleton, K & Garvie, S, “Self Harm: The Path to Recovery” (Oxford: Lion Hudson Plc, 2008) p13