In any industry, when an employee going to leaving job. Generally, employee gives resign letter to management for leave it's duties and responsibility from its designation. Once the management accept resign application letter, employee can be free from it's duties. And he is free to join any organization once the it get new job. It is standard practice in industry.
After the leave job, when any employee go for interview at any organization. Organization expecting the proof of previous job, it's resumes and company's overview about it's previous job. Interviewer presents the experience certificate as the proof and it's performance in previous job. Which is provides by organization who recently leave the job.
Here, as below sample experience certificate given, which may helpful for you.
Format in text which you copy and paste in your word file
date: 14th may 2006.
To whom so it may concern
This is to certify that “Mr. J.B.Smith” has been working here since 11 July 2005 to till date. He is our permanent employee on company payroll. He has been working here as works manager for last four years, his academic track record is nice to us, he is sincere & loyal to the company.
For, ABC Inc..