“A team is a small number of people with complementary skills who are committed to a common purpose, performance goals, and approach for which they are mutually accountable”
Team Building refers to a wide range of activities, presented to businesses, schools, sports teams, religious or nonprofit organizations designed for improving team performance. Team building is pursued via a variety of practices, and can range from simple bonding exercises to complex simulations and multi-day team building retreats designed to develop a team (including group assessment and group-dynamic games), usually falling somewhere in between. It generally sits within the theory and practice of organizational development, but can also be applied to sports teams, school groups, and other contexts.
Reasons for Team Building include:
-Improving communication 
-Making the workplace more enjoyable
-Motivating a team
-Getting to know each other
-Getting everyone “onto the same page”, including goal setting
-Teaching the team self-regulation strategies
-Helping participants to learn more about themselves (strengths and weaknesses)
-Identifying and utilizing the strengths of team members
-Improving team productivity
-Practicing effective collaboration with team members
stanacosmin | blog 
I really liked that you have included reasons of team building and that you described what is a team and what activities it might have. Also you have included some literature in your post which is really beneficial for those who want to read more about team building. You also have a picture which makes your post more interesting. I also would like to ask why did you include a picture with a person surrounded by many people?
The man who is on the floor represents a man who cannot work very well without support or a team and he has been discouraged so…With other words : “he needs to be part of a team”.