An HRIS, Human Resources Information System, is the database of record for your employees. Names, roles, compensation, benefits enrollment, time-off balances, documents, performance history, org structure. Modern HRIS platforms (Gusto, Rippling, BambooHR, Workday) bundle that record with the workflows that touch it: payroll, hiring, onboarding, performance reviews, compliance reporting. The strong ones eliminate spreadsheets and shared drives across 80% of HR ops; the weak ones add a fourth login to a problem that already needed fewer.
The category has fractured by company size. For startups under 50 employees, Gusto and Justworks dominate by bundling payroll + benefits + basic HR in one product, billed per active employee. For mid-market (50 to 500), BambooHR, Rippling, and HiBob compete with deeper HR workflows and configurability. For enterprise (500+), Workday, ADP Workforce Now, and SAP SuccessFactors handle multi-entity, multi-country complexity that mid-market tools fold under. Picking up-tier early is expensive; picking down-tier late is painful.
What you're actually buying is rarely the feature list, it's how the tool handles the moments that go wrong. Mid-year benefits enrollment changes. A multi-state employee who moves. A payroll correction that needs to flow into 401(k), state tax, and the employee's W-2. The strong HRIS platforms make these routine; the weak ones turn each into a four-email ticket with support.