1. Data - Data can be anything which is related or earth surface, can be also called it as Spatial Data because it holds the location(latitude and longitude). Spatial data is the most important component to do any work in GIS. If our data is wrong then the whole output will change. Using DBMS we can organize, manage and access both Spatial and Non-Spatial (tabular Data).
2. Software - Used to Edit, analyse, display your spatial data in the form of Maps and reports. There are both Commercial and Opensource software available to do these tasks.
3. Hardware - Hardware could be your Desktop(PC), laptop, Printer, Plotters, Server which we used to operate GIS Software.
4. Methods - How we process, analyse and preparing the final output using GIS Software. Here in-depth subject Knowledge plays a major role for an individual or for an organization.
5. People - Without technical people these all operations all highly impossible. In GIS Industry technical people vary from Analyst, Engineer, Scientist, Developers and Specialist who provide services, solutions and consultation to the end users.