Hello helensmith, welcome to Firewall.cx
On a general level, service accounts are standard user accounts that sometimes come already defined with the operating system. They are special accounts provided to run dedicated tasks such as backup processes or batch scripts that you might want to run automatically while the system is unattended or where you don't want to have to leave a normal user logged on.
Operating systems also contain their own processes or tasks that runs without user intervention in the background to do a specific job. In Windows these are called Services, and in unix-based OSs they are daemons. Again, each of these runs as a specific user with appropriate privileges and the accounts used for them often get called service accounts too.
For a good overview of this under Windows have a look at
Security is always an issue with this sort of arrangement, and if you're interested in that have a look at [url]
Hello I came accross a precise notes on service accounts, this is as follows:
"Microsoft SQL Server runs two services, SQL Server and SQL Server Agent. Service accounts are Windows user accounts used to start these services. Both local system and domain user accounts can be used. You can customize settings for each service. You can enter one logon account for both services, or specify either a local system account or a domain user account for each.
The local system account does not have network access rights in Windows NT 4.0 and Windows 2000, and restricts your SQL Server installation from interacting with other servers.
A domain user account uses Windows authentication, and is typically used because many server-to-server activities can be performed only with a domain user account. Therefore, you should define domain user accounts to SQL Server services while performing the following activities:
Remote procedure calls.
Backing up to network drives.
Heterogeneous joins that involve remote data sources.
Hope this will help you to get some good idea.