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+These explanations provide background knowledge for learning ehrQL.
+
+* [ehrQL backend tables](backend-tables.md)
+* [ehrQL output formats](output-formats.md)
+* [Using ehrQL in OpenSAFELY projects](using-ehrql-in-opensafely-projects.md)
+* [Running ehrQL](running-ehrql.md)
+* [Using the measures framework](measures.md)
+* [Selecting populations for study](selecting-populations-for-study.md)
+* [The OpenSAFELY VS Code extension](vscode-extension.md)