diff --git a/README.md b/README.md
index abc2c95..e68fb92 100644
--- a/README.md
+++ b/README.md
@@ -8,3 +8,5 @@
 [![Coverage](https://codecov.io/gh/JuliaGraphs/GraphProperties.jl/branch/main/graph/badge.svg)](https://codecov.io/gh/JuliaGraphs/GraphProperties.jl)
 [![PkgEval](https://JuliaCI.github.io/NanosoldierReports/pkgeval_badges/G/GraphProperties.svg)](https://JuliaCI.github.io/NanosoldierReports/pkgeval_badges/G/GraphProperties.html)
 [![Aqua](https://raw.githubusercontent.com/JuliaTesting/Aqua.jl/master/badge.svg)](https://github.com/JuliaTesting/Aqua.jl)
+
+Julia package for describing graph properties.
diff --git a/src/GraphProperties.jl b/src/GraphProperties.jl
index 8464daa..1bf12a2 100644
--- a/src/GraphProperties.jl
+++ b/src/GraphProperties.jl
@@ -1,5 +1,106 @@
 module GraphProperties
 
-# Write your package code here.
+export
+    GraphProperty,
+    PropertyComparison
+
+abstract type GraphProperty{T} end
+
+struct PropertyComparison{
+    Comparison <: Union{typeof(==), typeof(≤), typeof(≥)},
+    Property <: GraphProperty{<:Real},
+    Value,
+} <: GraphProperty{Bool}
+    comparison::Comparison
+    property::Property
+    value::Value
+end
+
+let
+    properties_abstractvector = Symbol[
+        :DegreeSequence,
+    ]
+    properties_real = Symbol[
+        :FractionalChromaticNumber,
+        :FractionalMatchingNumber,
+    ]
+    properties_integer = Symbol[
+        :NumberOfVertices,
+        :NumberOfEdges,
+        :NumberOfArcs,
+        :NumberOfConnectedComponents,
+        :MinimumDegree,
+        :MaximumDegree,
+        :Girth,
+        :VertexConnectivity,
+        :EdgeConnectivity,
+        :CliqueNumber,
+        :ChromaticNumber,
+        :ChromaticIndex,
+        :MatchingNumber,
+        :DominationNumber,
+        :IndependenceNumber,
+        :Choosability,
+        :FeedbackVertexSetNumber,
+        :VertexCoverNumber,
+        :EdgeCoverNumber,
+        :IntersectionNumber,
+        :BipartiteDimension,
+        :HadwigerNumber,
+        :TwinWidth,
+        :CliqueWidth,
+        :Treewidth,
+        :Pathwidth,
+        :Boxicity,
+        :Degeneracy,
+        :Arboricity,
+        :Splittance,
+    ]
+    properties_bool = Symbol[
+        :IsUndirectedGraph,
+        :IsDirectedGraph,
+        :DigraphIsDAG,
+        :DigraphIsOrientation,
+        :GraphIsConnected,
+        :DigraphIsWeaklyConnected,
+        :DigraphIsStronglyConnected,
+        :GraphIsBipartite,
+        :GraphIsPath,
+        :GraphIsCycle,
+        :GraphIsPlanar,
+        :DigraphIsPlanar,
+        :GraphIsTriangleFree,
+        :GraphIsComplete,
+        :GraphIsRegular,
+        :GraphIsPerfect,
+        :GraphIsTriviallyPerfect,
+        :GraphIsForest,
+        :GraphIsTree,
+        :GraphIsIndifferenceGraph,
+        :GraphIsIntervalGraph,
+        :GraphIsPtolemaic,
+        :GraphIsChordal,
+        :GraphIsMeynielGraph,
+        :GraphIsCircleGraph,
+        :GraphIsPermutationGraph,
+        :GraphIsCograph,
+        :GraphIsComparabilityGraph,
+        :GraphIsDistanceHereditary,
+        :GraphIsSplitGraph,
+    ]
+    for (typ, properties) ∈ (
+        (AbstractVector, properties_abstractvector),
+        (Real, properties_real),
+        (Integer, properties_integer),
+        (Bool, properties_bool),
+    )
+        for p ∈ properties
+            @eval export $p
+            @eval struct $p <: GraphProperty{$typ} end
+        end
+    end
+end
+
+# TODO: doc strings
 
 end