Trust does not need to involve belief in the good character, vices, or morals of the other party. Persons engaged in a criminal activity usually trust each other to some extent. Also, trust does not need to include an action that you and the other party are mutually engaged in. Trust is a prediction of reliance on an action, based on what a party knows about the other party. Trust is a statement about what is otherwise unknown -- for example, because it is far away, cannot be verified, or is in the future.
In the social sciences, the subtleties of trust are a subject of ongoing research. In sociology (and psychology) the degree to which one party trusts another is a measure of belief in the honesty, benevolence and competence of the other party. Based on the most recent research, a failure in trust may be forgiven more easily if it is interpreted as a failure of competence rather than a lack of benevolence or honesty.
From this perspective, trust is a mental state, which cannot be measured directly. Confidence in the results of trusting may be measured through behavior, or alternatively, one can measure self-reported trust (with all the caveat surrounding that method). Trust may be considered a moral choice[, or at least a heuristic, allowing the human to deal with complexities that outgo rationalistic reasoning. In this case, machine-human trust is meaningless, because computers have no moral sense and rely on rational computations. Any trust in a device under this characterization is computer-mediated trust of the user of the machine in the designer and creator of the device; who has implemented the rational rules into the device. Francis Fukuyama and Tyler are academics who advocate this conception of trust – as moral and not directly observable.
A second perspective in social theory comes from the classic Foundations of Social Theory by James S. Coleman. Coleman offers a four-part definition:
- 1. Placement of trust allows actions that otherwise are not possible (i.e. trust allows actions to be conducted based on incomplete information on the case in hand).
- 2. The person in whom trust is placed (trustee) is trustworthy, then the trustor will be better off than if he or she had not trusted. Conversely, if the trustee is not trustworthy, then the trustor will be worse off than if he or she had not trusted (this is reminiscent of a classical prisoner's dilemma).
- 3. Trust is an action that involves a voluntary transfer of resources (physical, financial, intellectual, or temporal) from the truster to the trustee with no real commitment from the trustee (again prisoner's dilemma).
- 4. A time lag exists between the extension of trust and the result of the trusting behavior.
The strength of Coleman's definition is that it allows for discussion of trust behavior. These discussions have been particularly useful in reasoning about human-computer trust, and trust behaviors.
A critical element in studies of trust behavior is power. One who is in a position of dependence cannot be said to trust another in a moral sense, but can be defined as trusting another in the most strict behavioral sense. Trusting another party when one is compelled to do so is sometimes called reliance, to indicate that the belief in benevolence and competence may be absent, while the behaviors are present. Others refer only to coercion.
Coleman's definition does not account for the distinction between trust (worthiness-see worship) as a moral attribute and trustworthiness as mere reliability. It is Annette Baier (Ethics, 1987) who characterizes contexts of trust as structures of interaction in which moral obligations act upon the trustees.
The substantive conflict in the social sciences is whether trust is entirely internal, and only confidence is observable, or whether trust behaviors (and self reported levels of trust) can meaningfully measure trust in the absence of coercion. Note however that many languages (e.g. Dutch or German) do not distinguish between the words trust and confidence, which is complicating this issue. The distinction between trust and confidence is an unsolved issue in current trust/confidence research.
In general, trust is essential as Social institutions (governments), economies, and communities require trust to function. Therefore trust and altruism are areas of study for economists, although these concepts go beyond strict rational economics.
In psychology, trust begins just from the birth of the child. Trust grows stronger as the child grows older. But the root of trust comes from the relationship between the mother or caregiver of the child. The strength in the family relies on the trust. If the family is very accepting and loving, the children will have a better grip on trusting others. If a child did not have a strong family to fall back on, they might have issues developing trust between friends and other family members. Trust is a very sacred thing and is hard to regain trust once lost. Many children are given blankets or teddy bears at birth that they end up keeping for most of their lives, or just their baby stage. The teddy bear or blanket is something that has been there for their whole life as the child knows it. Having either a teddy bear or blanket or even something that has been there for their whole life creates good trust.
Trust is integral to the idea of social influence: it is easier to influence or persuade someone who is trusting. The notion of trust is increasingly adopted to predict acceptance of behaviors by others, institutions (e.g. government agencies) and objects such as machines. However, once again perception of honesty, competence and value similarity (slightly similar to benevolence) are essential.There are three different forms of trust. Trust is being vulnerable to someone even though they are trustworthy; Trustworthiness is the ability to trust, and trust propensity being able to rely on them. Once trust is lost, by obvious violation of one of these three determinants, it is very hard to regain trust. Thus there is a clear a-symmetry in building versus destruction of trust. Hence being and acting trustworthy should be considered the only sure way to maintain a trust level.
Increasingly much research has been done on the notion of trust and its social implications:
- Barbara Misztal in her book attempts to combine all notions of trust together. She points out three basic things that trust does in the lives of people: It makes social life predictable, it creates a sense of community, and it makes it easier for people to work together.
- In the context of sexual trust Riki Robbins describes [http://www.innerself.com/Relationships/Four_Stages_of_Trust.htm four stages of trust.
- In the context of Information theory Ed Gerck defines and contrasts trust with social functions such as power, surveillance, and accountability
In addition to the social influence, in organizational settings, trust may have a positive influence on the behaviors, perceptions, and performances of a person. One factor that enhances trust in a human being is facial resemblance. Evidence shows through manipulation of facial resemblance in a two person sequential trust game that having similar facial features (facial resemblance) enhanced trust in their partner. Structure often creates trust in a person that encourages them to feel comfortable and excel in the workplace. Working anywhere may be stressful and takes effort. By having a conveniently organized area to work on, concentration will increase as well as effort. Structure is not just a method of order. It increases trust and therefore makes a workplace manageable. A structured, ordered environment produces trust as one may contain increased cooperation and perform on a higher level. People may work together and achieve success through trust, while working on projects that rely on each individual’s contribution. 
One's social relationship characterized by low trust and norms that discourage academic engagement are expected to be associated with low academic achievement. Individuals that are in relationships characterized by high levels of social trust are more apt to openly exchange information and to act with caring benevolence toward one another than those in relationships lacking trust. 
An important key to treating sexual victimization of a child is the rebuilding of trust between daughter and mother. Failure for the adults to validate the sexual abuse contributes to the child's difficulty trusting the self and others.  Trust is often affected by the erosion of a marriage. Children of divorce do not exhibit less trust in mothers, partners, spouses, friends, and associates than their peers of intact families. The impact of parental divorce is limited to trust in the father. 
Kelton; Fleischmann & Wallace (2008). Trust in Digital Information.
Kini, A., & Choobineh, J. (1998). Trust in electronic commerce:
- Barbara Misztal, Trust in Modern Societies: The Search for the Bases of Social Order, Polity Press, ISBN 0-7456-1634-8
- Riki Robbins, Betrayed!: How You Can Restore Sexual Trust and Rebuild Your Life, Adams Media Corporation, ISBN 1-55850-848-1
- Ed Gerck, in Trust Points, Digital Certificates: Applied Internet Security by J. Feghhi, J. Feghhi and P. Williams, Addison-Wesley, ISBN 0-20-130980-7, 1998.
- DeBruine, Lisa Facial. Resemblance Enhances Trust
- The Role of Trust in Organizational Settings, Kurt T. Dirks, Donald L. Ferrin, 2001
- Goddard, Roger. Relation Network, Social Trust, and Norms: A Social Capitol Perspective on Students' Chances of Academic Success
- TIMMONS-MITCHELL, JANE. TREATING SEXUAL VICTIMIZATION: DEVELOPING TRUST-BASED RELATING IN THE MOTHER-DAUGHTER DYAD
- King, Valarie. Parental Divorce and Interpersonal Trust in Adult Offspring
Bachmann, Reinhard and Zaheer, Akbar (eds.)(2006). Handbook of Trust Research. Cheltenham: Edward Elgar.
Bicchieri, Cristina, Duffy, John and Tolle, Gil (2004.) “Trust among strangers”, Philosophy of Science 71: 1-34.
Marková, I. & Gillespie, A. (Eds.) (2007). Trust and distrust: Socio-cultural perspectives. Greenwich, CT: Information Age Publishing, Inc.
Kelton, Kari; Fleischmann, Kenneth R. & Wallace, William A. (2008). Trust in Digital Information. JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, 59(3):363–374.
Kini, A., & Choobineh, J. (1998, January). Trust in electronic commerce: Definition and theoretical considerations. Paper presented at the Thirty-FirstnHawaii International Conference on System Sciences, Kohala Coast, HI.
- Trust Building Activities
- Trust: Making and Breaking Cooperative Relations, edited by Diego Gambetta
- Am I Trustworthy? (1950) Educational video clip
- Stony Brook University is presently (2006 through 2009) hosting weekly seminars on the issue of trust in the personal, religious, social, and scientific realms as part of the Templeton Foundation's Research Lecture series and all of the talks and discussions are recorded and available online: via iTunes. More detailed information and a list of the seminars and participants is available here
- World Database of Trust Harvey S. James, Jr., Ph.D (Updated August 2007) A variety of definitions of trust are collected and listed.