"An organized collection of computer hardware, software, geographic data, and personnel, designed to efficiently capture, store, update, manipulate, analyze and display all forms of geographically referenced information".
Put more simply though!
"It is a computer system capable of holding and using data describing places on the earth's surface".
GIS Technology can be used for scientific investigations, management of resources, development planning, and risk assessment. These criteria are even more important within the petroleum industry and GIS has the capabilities to answer all these questions and more within the one application/
ArcGIS is a desktop based, software program, used to create, edit, import, manage, query, analyze and publish geospatial data.
(Which are restricted to, low, middle and fully configured versions of the software).
The Tellus Toolbar is a custom built ArcGIS extension by Fugro Robertson Ltd., that resides within ArcMap.
A geodatabase is an object-oriented data model introduced by ESRI that represents geographic features and attributes as objects and the relationships between objects, but is hosted inside a relational database management system (RDBMS).
An SDE geodatabase is a remote geodatabase in an RDBMS (e.g. Oracle), served to client applications by ArcSDE. It can be read simultaneously by several users, and more than one user at a time can write data into it, by creating different versions of the data.
A personal geodatabase stores data in a single-user RDBMS (e.g. Access). It can be read simultaneously by many users, but only one user at a time can write data to it.
For an organisation that desires a large Tellus user group with various levels of users, varying from data viewers, to data generators and managers, then the SDE geodatabase solution for Tellus may be their best data repository. For an organisation with a small pool of users (<10), who wish only to view the Tellus data alongside their own data, then the Personal geodatabase solution for Tellus may be their best data repository.