The success of every great product or service hinges on the ability of the team to get things done. When you work as a team, you can complete projects on time with maximum results.
Here are a few reasons teamwork is important.
The Accountability Factor

When working together to achieve a common goal, team members hold each other accountable for meeting specific project milestones. Individuals feel a greater obligation to perform up to or exceed expectations when they are part of a team. When working alone, individuals are more likely to excuse failures or missed opportunities because there is less of a sense that the work matters. Working as a team reinforces the meaning behind and importance of the work.
Increased Learning Opportunities
When working as part of a team, you can learn from the other members of your team. Each person possesses a unique set of skills that other team members can leverage to expand the value and impact of their own contributions.

When you work alone, on the other hand, you may not have the same opportunities. You may miss out on growing your knowledge-base, resulting in achievements that may be significantly less impactful than the accomplishments of a team of individuals.
Mitigation of Risk
There is more of a risk of failure for single-contributor projects than for team projects. This is because the team project’s success typically does not hinge on the availability or reliability of a single individual. Should an individual suddenly not be available for a team project, the project is less likely to fail. Other members can pick up the abandoned work temporarily — or permanently, depending on the situation.
Teamwork helps mitigate the risk of failing to accomplish tasks.
Maximized Performance

One of the most important reasons that teams are more effective and efficient than individuals working alone is that often in teamwork, there is a synergy of performance.
The team works synergistically to remove milestones, share ideas, reinforce goals, redirect intentions, leverage skill sets, etc.
Teamwork is important because it focuses on a group of individuals with distinct talents and interests toward a common goal. The impact of this focused team effort is often more significant than the impact of any individual’s efforts. Consequently, teams typically produce better outcomes than do individuals working alone.