## 2 Theoretical Background and Hypotheses  
### Subjective Well-Being and Social Media  
Well-being is a subjective and related concept that represents one's positive self-appraisal about his/her life at a point or period [7; 12; 17]. Self-appraisal includes one's emotional reactions, moods, judgements about their life satisfaction, and fulfillment [12]. In this sense, previous studies consider well-being as the contentment, satisfaction, or happiness derived from optimal psychological functioning [17; 18]. On the other hand, some researchers suggest that well-being reflects one's sense of pleasure and accomplishment value based on one's overall evaluation of one's quality of life [19]. [PERSON] (2007) [20] also postulates that well-being represents one's positive mood, negative mood, and life satisfaction. Since previous the literature [7; 8] argues that communication technologies such as social media can enhance users' life quality and subjective well-being, in this study, we use the term \"subjective well-being\" to measure one's feelings and consciousness about social media use, such as pleasure perception, life satisfaction, and positive affective reactions.  
According to the expectancy theory of motivation [21], an individual's behavior could be motivated by the desirability of the outcomes [22]. Subjective well-being has been defined as the expected benefits that could motivate members to continue using social media [8]. Given that continued use determinesthe success of information technologies [13], such as social media, it is important to understand what can facilitate subjective well-being on social media. In fact, researchers have begun to explore the antecedents of subjective well-being. For example, [7] have found that social integration, social bonding, and social bridging are the antecedents of subjective well-being. Furthermore, [8] have reported that structural capital, relational capital, and cognitive capital are the predictors of subjective well-being.  
Although previous studies [7; 8] have demonstrated that social capital plays an important role in shaping subjective well-being, the factors affecting subjective well-being must be further clarified, because there are unexamined factors that may affect subjective well-being. Generally speaking, social media provides an attractive space for people to get or offer help [23]. Previous literature argues that receiving social support is a vital factor that determines subjective well-being in an organization [11; 16; 24]. However, it is unclear whether providing support to others in an online setting facilitates subjective well-being. In addition, researchers consider that the interpersonal relationships in a social unit will impact users' online support-seeking and online support-providing behaviors [14]. Based on the above arguments, we recognize that interpersonal relationships affect receiving and providing online support, which in turn impacts subjective well-being. However, such relationships among interpersonal relationships, social support, and subjective well-being have received little attention from researchers. Therefore, in this study, we aimed to examine the links among social capital, social-support activities, and subjective well-being.  
In addition, subject well-being is the scientific analysis of how an individual evaluates his/her life at a specific moment or period, as mentioned earlier. This implies that one's perception of well-being may be different during various periods, since the relationships between subjective well-being and its antecedents may change as online contacts increase over time. However, such potential exchanges in the relationships between subjective well-being and its antecedents have been overlooked by previous studies. To fill this knowledge gap, this study aimed to examine the influence of experience on the relationship between online support activities and subjective well-being.