# Knowledge: satellite data and space technology explained The knowledge section explains the terms and technologies behind satellite-based services for readers outside the space sector: what space-enabled solutions are, how Earth observation, satellite navigation and satellite communication work, and how to procure such services. Each page lists the public sources behind its statements. ## Where to start If you are new to the field, read the definition of space-enabled solutions first: it shows how the three space technologies and AI fit together. Then read the page on the technology your task depends on. When you are planning a purchase, the procurement guide takes you from the decision the data must support to the evaluation of offers. ### What are space-enabled solutions? The definition, the building blocks, the European programmes behind them and how an organisation introduces a solution. [Read the definition](https://leto.space/knowledge/space-enabled-solutions/) ### How to procure Earth observation and satellite services Six steps for cities and companies, from the decision to the evaluation of offers, with a checklist for each step. [Read the guide](https://leto.space/knowledge/procurement-guide/) ## The three space technologies Each page explains one technology: how it works, what it is used for, which European programmes provide it and where its limits are. ### What is Earth observation? Optical and radar data, resolution and revisit, Copernicus and free data, and commercial imagery. [Earth observation explained](https://leto.space/knowledge/earth-observation/) ### What is GNSS? Satellite navigation: positioning, navigation and timing, and the European systems Galileo and EGNOS. [GNSS explained](https://leto.space/knowledge/gnss/) ### What is satellite communication? How satellite links work, GEO and LEO satellites, when satellite connectivity makes sense for a business, and GOVSATCOM and IRIS². [Satellite communication explained](https://leto.space/knowledge/satellite-communication/) ## Where to go next - [Browse use cases](https://leto.space/use-cases/): Applications of space technology by industry, technology and challenge. - [Our consulting](https://leto.space/consulting/): From the first question to a solution in operation. Page: