What overselling means
Overselling allows a reseller to allocate more package limits than the server will use at one time. It needs careful monitoring.
Reseller Hosting Guide
Overselling in Reseller Hosting Explained
Understand how overselling works, when it becomes risky, and how to choose reseller hosting with enough real resources for customer websites.
Where risk starts
Problems appear when too many active websites use CPU, memory, inode, email, or bandwidth resources at the same time.
Better planning
Pick a reseller plan based on expected active usage, customer type, support needs, backup policy, and upgrade path — not only headline disk space.