Employee Engagement And Retention

A company is an environment where people work hard to earn their living.
Employers and employees both have their part of roles to play. But apart from this, a company should consist of employees and retention. But my question is, what are employee engagement and retention?
1- Employee engagement is the way to measure the connection between employees and employers. They care for their job as well as the success of their coworkers.
2-Employee retention is the ability of an organization to prevent employee turnover or the number of people who leave their job in a short period.