diff --git a/.gitignore b/.gitignore
index 31e1fcd..7e6db21 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,3 @@
-node_modules/
 .idea/
+node_modules/
 .DS_Store
diff --git a/.npmignore b/.npmignore
new file mode 100644
index 0000000..2befdd2
--- /dev/null
+++ b/.npmignore
@@ -0,0 +1,6 @@
+.github/
+.idea/
+node_modules/
+test/
+.DS_Store
+.editorconfig
diff --git a/package.json b/package.json
index be98b39..4241c33 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "version": "1.0.0",
   "description": "A library to help you with family name prepositions in Dutch last names.",
   "main": "./src/index.js",
+  "types": "./src/index.d.ts",
   "scripts": {
     "test": "NODE_OPTIONS=--experimental-vm-modules jest"
   },
diff --git a/src/dutchPrepositions.js b/src/dutchPrepositions.js
index c1d3cc4..9d6b025 100644
--- a/src/dutchPrepositions.js
+++ b/src/dutchPrepositions.js
@@ -5,6 +5,8 @@
 // - van de
 // - van
 
+// Based on https://nl.wikipedia.org/wiki/Tussenvoegsel
+
 const DutchPrepositons = [
     "aan den ",
     "aan der ",
diff --git a/src/index.d.ts b/src/index.d.ts
new file mode 100644
index 0000000..85c813a
--- /dev/null
+++ b/src/index.d.ts
@@ -0,0 +1,60 @@
+/**
+ * Searches the specified last name for a preposition.
+ * Optionally applies search options, if provided.
+ *
+ * @param lastName The last name to extract a preposition from.
+ * @param options (Optional) The options to apply to the search.
+ * @returns A FindPrepositionResult
+ */
+export function findPreposition(lastName: String, options?: FindPrepositionOptions): FindPrepositionResult;
+
+export interface FindPrepositionOptions {
+    /**
+     * The array of prepositions to use. Uses the default bundled list if not specified.
+     * When supplying your own list, make sure your prepositions end with a space when there
+     * is a space between the preposition and the last name, otherwise the trailing space
+     * would get included in the last name.
+     *
+     * Defaults to {@link DutchPrepositions}.
+     */
+    prepositions?: String[];
+
+    /**
+     * An array of prepositions to exclude from the list. Useful if you want to exclude a specific preposition
+     * from the default list. Keep in mind you'll need to end most prepositions with a trailing space.
+     *
+     * Defaults to an empty array.
+     */
+    exclude?: String[];
+
+    /**
+     * Ignores a preposition if no other characters remain after matching it.
+     *
+     * Defaults to true.
+     */
+    ignoreIfNoSuffix?: Boolean;
+
+    /**
+     * Strips the trailing space from the preposition.
+     *
+     * Defaults to false.
+     */
+    stripTrailingSpace?: Boolean;
+}
+
+export interface FindPrepositionResult {
+    /**
+     * The found preposition, or null if nothing was found.
+     */
+    preposition: String | null;
+
+    /**
+     * The last name without the preposition, or null if the name would be an empty string.
+     */
+    lastName: String | null;
+}
+
+/**
+ * A list of the most common Dutch prepositions, based on the Wikipedia article: https://nl.wikipedia.org/wiki/Tussenvoegsel
+ */
+export const DutchPrepositions: String[];