A service account is a user account that is created explicitly to provide a security context for services running on Windows Server operating systems. The security context determines the service's ability to access local and network resources. The Windows operating systems rely on services to run various features.
What is the difference between user and service account?
User accounts are used by real users, service accounts are used by system services such as web servers, mail transport agents, databases.
A service account is a user account that has been created to run a particular piece of software or service. The principle of least privilege is giving the user only the minimum required amount of access. For example, if a user only requires access to certain files then they should only have access to those files.