You do a good job technically, and the management takes notice, and promotes you to be a Project Manager.
You are now required to do Project Management. However, the skills required to be a successful and effective Project Manager are very different from doing the technical work individually.
Now, to manage a project successfully, you need to have people management skills, handle difficult customers, sponsors, stakeholders, and an ever changing set of requirements.
Project Management is not easy. It is better to learn and acquire Project management skills at the earliest, so that you do not suffer, and begin to deliver higher value to your clients, and bosses.
Project Management Institute (PMI.org), a not-for-profit organization based in the United States of America, has come up with a set of best practices for managing projects across a diverse set of industries, and is a holistic view of managing small, medium or large scale projects with ease. It is called the Project Management Body of Knowledge (PMBOK Guide)
PMI has also created an examination, called the Project Management Professional (PMP) Certification exam, based on the PMBOK Guide
Over the years, PMI’s PMP Certification