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+# Grids and grid functions
+
+The submodule `Grids` aims to provide types and logic for all types of grids that are useful for implementing summation-by-parts difference methods. It provides an abstract top level type `Grid` which defines a broad interface for how a general grid is supposed to work. Currently only equidistant grids are supported, but the basic structure supports implementations of curvilinear grids, multi-block grids, periodic grids and much more.
+
+The module also has functionality for creating and working with grid functions.
+
+## Interface for grids
+All grids are expected to work as a grid function for the coordinate function, and thus implements Julia's Indexing- and Iteration-interfaces. Notably they are *not* abstract arrays because that inteface is too restrictive for the types of grids we wish to implement.
+
+## To write about
+<!-- # TODO: -->
+* Grid functions
+  * Basic structure
+     * Indexing
+  * Curvilinear
+  * Multiblock
+  * Vector valued grid functions