Sexual identity is how one thinks of oneself in terms of to whom one is romantically or sexually attracted.
 "Sexual identity" may also refer to sexual orientation identity, which is when people identify or dis-identify with a sexual orientation or choose not to identify with a sexual orientation.
 Sexual identity and sexual behavior are closely related to sexual orientation, but they are distinguished, with "identity" referring to an individual's conception of themselves, "behavior" referring to actual sexual acts performed by the individual, and "sexual orientation" referring to romantic or sexual attractions toward persons of the opposite sex or gender, the same sex or gender, to both sexes or more than one gender, or to no one.
The Kinsey scale, also called the Heterosexual–Homosexual Rating Scale, is used in research to describe a person's sexual orientation based on their experience or response at a given time.
 The scale typically ranges from 0, meaning exclusively heterosexual, to 6, meaning exclusively homosexual.
 In both the Male and Female volumes of the "Kinsey Reports", an additional grade, listed as "X", was used to mean "no socio-sexual contacts or reactions".
 The reports were first published in "Sexual Behavior in the Human Male" (1948) by Alfred Kinsey, Wardell Pomeroy and others, and were also prominent in the complementary work "Sexual Behavior in the Human Female" (1953).
The historical concept and definition of sexual orientation varies and has changed greatly over time; for example the word "gay" was not used to describe sexual orientation until the mid 20th century.
 A number of different classification schemes have been used to describe sexual orientation since the mid-19th century, and scholars have often defined the term "sexual orientation" in divergent ways.
 Indeed, several studies have found that much of the research about sexual orientation has failed to define the term at all, making it difficult to reconcile the results of different studies.
 However, most definitions include a psychological component (such as the direction of an individual's erotic desire) and/or a behavioural component (which focuses on the sex of the individual's sexual partner/s).
 Some prefer to simply follow an individual's self-definition or identity.
Sexual fluidity is one or more changes in sexuality or sexual identity (sometimes known as sexual orientation identity).
 There is significant debate over whether sexuality is stable throughout life or is fluid and malleable.
 Scientific consensus is that sexual orientation, unlike sexual orientation identity, is not a choice.
 While scientists generally believe that sexual orientation is usually stable (unlikely to change), sexual identity can change throughout an individual's life, and may or may not align with biological sex, sexual behavior or actual sexual orientation.
<ref name="Concordance/discordance in SO"> </ref> There is no consensus on the exact cause of developing a sexual orientation, but genetic, hormonal, social and cultural influences have been examined.
 Scientists believe that it is caused by a complex interplay of genetic, hormonal, and environmental influences.
Scales of sexual orientation are classification schemes of different sexual orientations. Definitions of the term "sexual orientation" normally include two components: the "psychological" and the "behavioral" component, but the definitions of the two components vary between researchers and across time.
 Those difficulties motivate researchers to define scales to measure and describe sexual orientation.
 Most sexual behavior and sexual orientation scales are motivated by the view that sexual orientation is a continuum.
 The Kinsey scale works from a continuum viewpoint and is the most prevalent sexual orientation scale.
Ego-dystonic sexual orientation is an ego-dystonic mental disorder characterized by having a sexual orientation or an attraction that is at odds with one's idealized self-image, causing anxiety and a desire to change one's orientation or become more comfortable with one's sexual orientation.
 It describes not innate sexual orientation itself, but a conflict between the sexual orientation one wishes to have and the sexual orientation one actually possesses.
The historical concept and definition of sexual orientation varies and has changed greatly over time; for example the word "gay" was not used to describe sexual orientation until the mid 20th century.
 A number of different classification schemes have been used to describe sexual orientation since the mid-19th century, and scholars have often defined the term "sexual orientation" in divergent ways.
 Indeed, several studies have found that much of the research about sexual orientation has failed to define the term at all, making it difficult to reconcile the results of different studies.
 However, most definitions include a psychological component (such as the direction of an individual's erotic desire) and/or a behavioural component (which focuses on the sex of the individual's sexual partner/s).
 Some prefer to simply follow an individual's self-definition or identity.
The Klein Sexual Orientation Grid (KSOG) developed by Fritz Klein attempts to measure sexual orientation by expanding upon the earlier Kinsey scale.
 Klein first described the KSOG in his 1978 book "The Bisexual Option".
The Sex Orientation Scale (SOS) was Harry Benjamin's attempt to classify and understand various forms and subtypes of transvestism and transsexualism in biological males, published in 1966.
 It was a seven-point scale (with three types of transvestism, three types of transsexualism, and one category for typical males); it was analogous to the Kinsey Scale as it relates to sexual orientation, which also had seven categories.
 Much like Kinsey's understanding of sexual orientation, Benjamin understood the nature of gender identity and gender expression not as a discrete scale, but as a spectrum, a continuum with many variations.
 However the Benjamin scale does not reflect a modern understanding of gender identity and is not useful as a contemporary diagnostic tool, especially due to its conflation of gender identity with sexual orientation.
Gay, Straight, and the Reason Why: The Science of Sexual Orientation (2010; second edition 2016) is a book about the development of sexual orientation by the neuroscientist Simon LeVay, in which the author argues that sexual orientation is an aspect of gender that emerges from the prenatal sexual differentiation of the brain, and criticizes Freudian and behaviorist explanations of sexual orientation.
 "Gay, Straight, and the Reason Why" received numerous positive reviews, praising it for LeVay's wide-ranging overview of scientific research on sexual orientation, but the book also received some mixed or negative reviews, criticizing it on grounds such as LeVay's willingness to rely on studies with inadequate sample sizes.
 In 2012, "Gay, Straight, and the Reason Why" received the Bullough Book Award for the most distinguished book written for the professional sexological community published in a given year.

Question: The scales of sexual orientation and the Kinsey scale are both what?
Answer: classification schemes