Tools
GIS tools most companies use
A short list of the programs that show up on most map teams.
Companies do not all use the same GIS. A few names come up over and over.
ArcGIS, from Esri, is the one most people mean when they say GIS. Cities, utilities, and consultants use ArcGIS Pro on the desktop and ArcGIS Online for maps in a browser. If a job posting says GIS, it often means ArcGIS.
QGIS is free. Smaller teams, schools, and a lot of offices outside large utilities use it. It opens the same kinds of files. It does not cost a license. Many people learn on QGIS and then move to ArcGIS at work, or the other way around.
GE Smallworld is common at large gas and electric companies. It is built for utility networks, not for general maps. Atmos Energy maps that I worked on were in Smallworld. You will see it less in city planning offices and more in pipe-and-wire companies.
A few other tools sit next to these.
AutoCAD is still used for design drawings. Those drawings are not always the live GIS. Someone may have to bring the drawing into the GIS after the job is built.
Google Earth and plain web maps are fine for a quick look at a neighborhood. They are not the record of a pipe.
Field apps collect the work outside. Esri Field Maps is common. On gas construction jobs, LocusView is a common as-built tool. The phone app is not a second map of record. It feeds the office map.
If you are choosing what to learn first, learn ArcGIS. Then learn how a file moves from a field app into that map. The product names change by company. The handoff is the part that matters.