In virtual worlds, people have digital representations that allow them to recognize each other, interact with other users and navigate in the virtual space. These representations are referred to as “avatars” and they can be two dimensional images, three dimensional figures as shown in Figure 1, icons, textual descriptions or a combination of all of these . Other components which can define an avatar include emotions, voice, gestures, textual font and background colors . Such avatars are used sometimes to bridge the gap between the virtual space and the real world ; an avatar can send a message to be displayed in a mirrored message wall in the real world, as shown in Figure 8.
Users differ in their choices of avatars in that some try to reflect their real life identities in the virtual world, others define a character from their imagination, whilst some users try to have ideal versions of themselves. In , the authors classified the behavior of user avatar creation into four categories:
1. “Roleplayers” who try to be completely different from their real world identities and attempt to have more than one avatar in the virtual space.
2. “Ideals” who try to have better and ideal representations of themselves in the synthetic world.
3. “Realistics” who try to have the same real world identities in their virtual worlds.
4. “Fantasies” who have only one avatar and try to be someone else in the online community.
In addition, the author of  divides the relationship between a person in the real world with his/her avatar in the virtual world into three identities in that the person is the real identity, the avatar is the virtual identity and the projective identity acts as a medium between the two by governing and guiding the actions of the real person that will be reflected by the avatar.
According to , avatar-to-avatar interactions in virtual worlds are similar to human-to-human interactions in the real world. Interestingly, the interactions between avatars are more similar to natural interactions in the real life than to virtual interactions in online social network sites such as Facebook . Therefore, as designers of a virtual world system we have to consider the type of users that our system is targeting and offer avatar customization tools that give them the ability to express themselves; this is intended to improve their user experience.
As in real worlds, building good reputations for avatars, appropriate social relationships and protecting their privacy are important consideration in virtual worlds . One of the important considerations in our system which aims to increase the level of trust in the synthetic world  is to allow the users to construct unique, identifiable and permanent representations of themselves in the virtual world.
Furthermore, the system will provide templates that allow the construction of different personalities in the virtual space (e.g. faces and hair styles). For example, Figure 2, Figure 3, Figure 4, Figure 5 and Figure 6 show examples of avatar customization tools in Second Life, World of Craft and Maple Story [2, 3 and 4]. In trying to understand the essential features of avatar customization systems that are preferred by virtual world users, the authors of  surveyed 180 users of Second Life, Maple Story and World of Craft. They asked respondents to rate different aspects that are related to avatars (e.g. hair, face, shoes and skin color) to know the most important part for customizing and personalizing an avatar in the virtual space .
The results showed that most users considered hair styles and hair colors as the most important factors and that 68% of them reported that they create avatars that are different from their real identities, such as choosing a different hair colour. However, they found that it is less often to encounter extreme or fundamentally divergent differences . The author’s state that hair colors and hair styles are simple appearance properties that help in creating a unique avatar that is visible, recognisable and reflect specific properties about the user such as his/her age, style and ethnicity .
To increase the level of immersion between the users, the system will have tools that allow private conversations (e.g. voice chat) to take place between avatars . From an ethical perspective, the moderation of a community with features designed for this are included in the system to allow the moderation of content posted by avatars. As it was mentioned in  that people tend to have the same rules and values in virtual worlds and real worlds.
Victoria McArthur  studied the ethical issues of having an avatar for a company or an organization in the virtual space for the purpose of advertising their products or use the virtual world as a recruitment tool as shown in Figure 7. For instance, the intellectual property rights associated with avatars created by companies’ representatives and whether these avatars are owned by the companies or their representatives. The author also studied whether the appearances of avatars impact the success of businesses or not .
Interestingly, the findings in [1 & 2] demonstrated that the interviewed users indicated that having a complex avatar with 3D images in not a pre-requisite of having an appealing avatar that they could engage with. Additionally, it was noted that avatar customization systems don’t have to offer very detailed and complex features in order to offer better or more appealing service for users. Furthermore, the majority of users in this study state that they have only one avatar in each virtual world . In Leapin.it! system, an avatar is represented by a 2D image with a username is unique, anonymous in that it doesn’t have to be their real name.
 Marion Boberg, Petri Piippo, and Elina Ollila. 2008. Designing avatars. In Proceedings of the 3rd international conference on Digital Interactive Media in Entertainment and Arts (DIMEA ’08). ACM, New York, NY, USA, 232-239. DOI=10.1145/1413634.1413679 http://doi.acm.org/10.1145/1413634.1413679
 Neustaedter, Carman, and Elena Fedorovskaya. “Presenting identity in a virtual world through avatar appearances.” Proceedings of Graphics Interface 2009. Canadian Information Processing Society, 2009.
 Ducheneaut, Nicolas, et al. “Body and mind: a study of avatar personalization in three virtual worlds.” Proceedings of the SIGCHI Conference on Human Factors in Computing Systems. ACM, 2009.
 McArthur, Victoria. “Real ethics in a virtual world.” CHI’08 extended abstracts on Human factors in computing systems. ACM, 2008.
 Gee, J.P., What video games have to teach us about learning and literacy. Palgrave MacMillan, New
York, NY, USA, 2003.
 Yeom, Jung-ho, and Beng-Kiang Tan. “Mirrored message wall: sharing between real and virtual space.” CHI’10 Extended Abstracts on Human Factors in Computing Systems. ACM, 2010.
 Varvello, Matteo, and Geoffrey M. Voelker. “Second life: a social network of humans and bots.” Proceedings of the 20th international workshop on Network and operating systems support for digital audio and video. ACM, 2010.
Edited by: MJD