"GIS" (Geographic Information System) usually means desktop software — a specialist opens a program like QGIS or ArcGIS, loads a set of files, and produces a map. It works, but it lives on one machine, with one trained operator, and the output is usually a static map or report that gets emailed around.
"Web GIS" is the same underlying idea — spatial data, layered and analyzed — delivered through a browser instead of a desktop application. Anyone in the department with a login can open a link, see the current map, filter it, and in some cases add data from the field. No GIS software needs to be installed on their machine.
What changes for staff day-to-day
With desktop GIS, only the trained GIS operator can open, edit, or export anything. Everyone else waits for that person to produce a PDF or printout. With Web GIS, a planning officer, a field inspector, or a department head can log in directly and see live data — filtered to their zone, their project, or their date range — without asking anyone to run a report for them.
This also changes how current the data is. A desktop GIS map is a snapshot from whenever it was last exported. A Web GIS dashboard reflects the latest uploaded survey, satellite pass, or field update, because it's reading from a live dataset rather than a static file.
What it costs to maintain
Desktop GIS software is typically a one-time or annual license cost per seat, plus the ongoing cost of a trained specialist to operate it. Web GIS shifts the cost structure toward hosting and a subscription or annual maintenance contract (AMC) — because now there's a server, a database, and an application to keep running and secure — but it removes the bottleneck of needing a specialist for every request.
The honest trade-off: Web GIS is not free just because it's "in the cloud." Budget for hosting, maintenance, and periodic updates the same way you would for any other departmental software system, not as a one-time purchase.
What to ask a vendor before signing
Where is the data hosted, and does that meet your department's data-residency requirements? Who owns the data if you switch vendors later? Can it work offline for field staff with unreliable connectivity, and sync when connection returns? What's included in the AMC versus billed separately? And critically — can your own staff use it without a GIS background, or does it still require a specialist operator, in which case you haven't actually solved the original bottleneck?