Directly from Wikipedia: Managed Services:
Managed services is the practice of outsourcing the responsibility for maintaining, and anticipating need for, a range of processes and functions, ostensibly for the purpose of improved operations and reduced budgetary expenditures through the reduction of directly-employed staff.
When it comes to Magento managed services, PowerSync offers:
Magento ongoing security patching services & security audits;
Magento ongoing platform upgrade services;
Magento performance tuning & SEO optimization services;
Magento custom development, platform customization, and integrations;
Fractional CTO services;
Application architecture audits;
Staff augmentation (PM, QA, Developer, Infrastructure, and UX talent).