diff --git a/app/src/main/java/acr/browser/lightning/database/history/HistoryModel.java b/app/src/main/java/acr/browser/lightning/database/history/HistoryModel.java
index 3660584..185ebcf 100644
--- a/app/src/main/java/acr/browser/lightning/database/history/HistoryModel.java
+++ b/app/src/main/java/acr/browser/lightning/database/history/HistoryModel.java
@@ -23,6 +23,11 @@ public final class HistoryModel {
 
     private HistoryModel() {}
 
+    /**
+     * An observable that deletes browser history.
+     *
+     * @return a valid observable.
+     */
     @NonNull
     public static Completable deleteHistory() {
         return Completable.create(new CompletableAction() {
@@ -37,6 +42,13 @@ public final class HistoryModel {
         });
     }
 
+    /**
+     * An observable that deletes the history
+     * entry with the specific URL.
+     *
+     * @param url the URL of the item to delete.
+     * @return a valid observable.
+     */
     @NonNull
     public static Completable deleteHistoryItem(@NonNull final String url) {
         return Completable.create(new CompletableAction() {
@@ -51,6 +63,16 @@ public final class HistoryModel {
         });
     }
 
+    /**
+     * An observable that visits the URL by
+     * adding it to the database if it doesn't
+     * exist or updating the time visited if
+     * it does.
+     *
+     * @param url   the URL of the item that was visited.
+     * @param title the title of the item that was visited.
+     * @return a valid observable.
+     */
     @NonNull
     public static Completable visitHistoryItem(@NonNull final String url, @Nullable final String title) {
         return Completable.create(new CompletableAction() {
@@ -65,6 +87,18 @@ public final class HistoryModel {
         });
     }
 
+    /**
+     * An observable that finds all history items
+     * containing the given query. If the query
+     * is contained anywhere within the title or
+     * the URL of the history item, it will be
+     * returned. For the sake of performance, only
+     * the first five items will be emitted.
+     *
+     * @param query the query to search for.
+     * @return a valid observable that emits
+     * a list of history items.
+     */
     @NonNull
     public static Single<List<HistoryItem>> findHistoryItemsContaining(@NonNull final String query) {
         return Single.create(new SingleAction<List<HistoryItem>>() {
@@ -79,6 +113,13 @@ public final class HistoryModel {
         });
     }
 
+    /**
+     * An observable that emits a list of the
+     * last 100 visited history items.
+     *
+     * @return a valid observable that emits
+     * a list of history items.
+     */
     @NonNull
     public static Single<List<HistoryItem>> lastHundredVisitedHistoryItems() {
         return Single.create(new SingleAction<List<HistoryItem>>() {