Computer games are evolving from day-to-day and it is loved by almost all age of children. It is used in educational settings to improve students' motivation and learning capabilities. Compared to traditional learning methods, they have been gaining a particular advantage regarding their ability to support and promote user engagement.

One of the greatest and newest changes among the computer games is virtual character technology.

Role of Virtual Characters

Virtual characters can take on several kinds of roles: as avatar (the self representation of user), tutor, learning companion, actor, and etc.

• Avatar: It is a human body representation in the virtual worlds and each avatar has a visual graphical appearance. For example, avatar Heather in Google Lively (http://www.lively.com/html/landing.html), and avatars in Club Penguin (http://www.clubpenguin.com/ ).

• Tutor: It is a virtual character that plays an authoritative role in a learning environment. A tutor may ask questions, provide feedback or grant award to learners. For example, in Abilities Builder Fraction Facts (http://www.freedownloadmanager.org/ ), a parrot character Peedy is designed to provide verbal and visual feedback. Peedy helps make the learning of fractions easier and fun.

• Learning Companion: It is a virtual character that plays a non-authoritative role in a learning environment and it may collaboratively work with the learner, provide hints or give suggestions to the learner during the learning process.
• Actor: It is other characters act in the game to make the environment more fun.

Type of Virtual Characters

From the aspect that whether the appearance of a virtual character is real life like, we can have life-like virtual characters, and cartoon like virtual characters.

We can also categorize virtual characters as explanatory and non-explanatory virtual characters based on whether they can speak; emotional and non-emotional virtual characters based on whether they have emotion, and so on.

Importance of Virtual Characters

• Virtual character allows the creation of an fun educational environment. It helps to stimulate children's interest and therefore it can add motivational value to learning. Through the movement or speech of virtual characters, it can also help to keep children's attention to the context during learning.
• Virtual characters as the interface agents was a logical step in the evolution of graphic user interfaces. It allows the user to join a ‘face to face' communication with the interface agent who provides a mutual information exchange.
• For educational game/software, the virtual characters are called pedagogical agents. These agents usually have understanding of the educational context in order to be able to play useful roles in learning scenarios for children.