diff --git a/examples/xtd.core.examples/README.md b/examples/xtd.core.examples/README.md
index 7cebf87a5380..75226cfcedf3 100644
--- a/examples/xtd.core.examples/README.md
+++ b/examples/xtd.core.examples/README.md
@@ -286,6 +286,7 @@
 * [thread](threading/thread/README.md) shows hows how to use [xtd::threading::thread](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1thread.html) class.
 * [thread_pool](threading/thread_pool/README.md) shows hows how to use [xtd::threading::thread_pool](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1thread__pool.html) class.
 * [timeout](threading/timeout/README.md) shows how to use [xtd::threading:timeout](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1timeout.html) class.
+* [timer](threading/timeout/README.md) shows how to use [xtd::threading:timer](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1timer.html) class.
 * [wait_handle](threading/wait_handle/README.md) shows how to use [xtd::threading:wait_handle](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1wait__handle.html) class.
 
 ## [Uri](uri/README.md)
diff --git a/examples/xtd.core.examples/threading/CMakeLists.txt b/examples/xtd.core.examples/threading/CMakeLists.txt
index 5486ec997235..55401566f596 100644
--- a/examples/xtd.core.examples/threading/CMakeLists.txt
+++ b/examples/xtd.core.examples/threading/CMakeLists.txt
@@ -16,5 +16,6 @@ add_projects(
   thread
   thread_pool
   timeout
+  timer
   wait_handle
 )
diff --git a/examples/xtd.core.examples/threading/README.md b/examples/xtd.core.examples/threading/README.md
index d44a67606e6a..855d98e1f401 100644
--- a/examples/xtd.core.examples/threading/README.md
+++ b/examples/xtd.core.examples/threading/README.md
@@ -14,4 +14,5 @@
 * [thread](thread/README.md) shows hows how to use [xtd::threading::thread](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1thread.html) class.
 * [thread_pool](thread_pool/README.md) shows hows how to use [xtd::threading::thread_pool](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1thread__pool.html) class.
 * [timeout](timeout/README.md) shows how to use [xtd::threading:timeout](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1timeout.html) class.
+* [timer](timeout/README.md) shows how to use [xtd::threading:timer](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1timer.html) class.
 * [wait_handle](wait_handle/README.md) shows how to use [xtd::threading:wait_handle](https://gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1wait__handle.html) class.
diff --git a/examples/xtd.core.examples/threading/timer/CMakeLists.txt b/examples/xtd.core.examples/threading/timer/CMakeLists.txt
new file mode 100644
index 000000000000..4b9e9ac8d5be
--- /dev/null
+++ b/examples/xtd.core.examples/threading/timer/CMakeLists.txt
@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.5)
+
+project(timer)
+find_package(xtd REQUIRED)
+add_sources(README.md src/timer.cpp)
+target_type(CONSOLE_APPLICATION)
diff --git a/examples/xtd.core.examples/threading/timer/README.md b/examples/xtd.core.examples/threading/timer/README.md
new file mode 100644
index 000000000000..70fbca4b20ee
--- /dev/null
+++ b/examples/xtd.core.examples/threading/timer/README.md
@@ -0,0 +1,49 @@
+# thread_pool
+
+Shows how to use [xtd::threading::thread_pool](https:gammasoft71.github.io/xtd/reference_guides/latest/classxtd_1_1threading_1_1thread_pool.html) class.
+
+## Sources
+
+[src/thread_pool.cpp](src/thread_pool.cpp)
+
+[CMakeLists.txt](CMakeLists.txt)
+
+# Build and run
+
+Open "Command Prompt" or "Terminal". Navigate to the folder that contains the project and type the following:
+
+```cmake
+xtdc run
+```
+
+# Output
+
+```
+08:45:24.070 Creating timer.
+
+08:45:25.076 Checking status  1.
+08:45:25.333 Checking status  2.
+08:45:25.591 Checking status  3.
+08:45:25.847 Checking status  4.
+08:45:26.101 Checking status  5.
+08:45:26.365 Checking status  6.
+08:45:26.611 Checking status  7.
+08:45:26.864 Checking status  8.
+08:45:27.118 Checking status  9.
+08:45:27.375 Checking status 10.
+
+Changing period to .5 seconds.
+
+08:45:27.885 Checking status  1.
+08:45:28.389 Checking status  2.
+08:45:28.897 Checking status  3.
+08:45:29.402 Checking status  4.
+08:45:29.913 Checking status  5.
+08:45:30.414 Checking status  6.
+08:45:30.922 Checking status  7.
+08:45:31.428 Checking status  8.
+08:45:31.934 Checking status  9.
+08:45:32.445 Checking status 10.
+
+Destroying timer.
+```
diff --git a/examples/xtd.core.examples/threading/timer/src/timer.cpp b/examples/xtd.core.examples/threading/timer/src/timer.cpp
new file mode 100644
index 000000000000..d9f0c9668fa9
--- /dev/null
+++ b/examples/xtd.core.examples/threading/timer/src/timer.cpp
@@ -0,0 +1,99 @@
+#include <xtd/threading/auto_reset_event>
+#include <xtd/threading/timer>
+#include <xtd/console>
+#include <xtd/date_time>
+#include <xtd/random>
+#include <xtd/startup>
+
+using namespace xtd;
+using namespace xtd::threading;
+
+namespace timer_example {
+  class status_checker {
+  private:
+    int invoke_count = 0;
+    int max_count = 0;
+    
+  public:
+    status_checker(int count) {
+      invoke_count = 0;
+      max_count = count;
+    }
+    
+    // This method is called by the timer delegate.
+    void check_status(std::any state_info) {
+      auto auto_event = as<auto_reset_event>(state_info);
+      auto now = date_time::now();
+      console::write_line("{:t}.{:D3} Checking status {,2}.",
+                          now, now.millisecond(),
+                          ++invoke_count);
+      
+      if (invoke_count == max_count) {
+        // Reset the counter and signal the waiting thread.
+        invoke_count = 0;
+        auto_event.set();
+      }
+    }
+  };
+
+  class program {
+  public:
+    static void main() {
+      // Create an auto_reset_event to signal the timeout threshold in the
+      // timer callback has been reached.
+      auto auto_event = auto_reset_event {false};
+      
+      auto status_checker = timer_example::status_checker {10};
+      
+      // Create a timer that invokes check_status after one second,
+      // and every 1/4 second thereafter.
+      auto now = date_time::now();
+      console::write_line("{:t}.{:D3} Creating timer.\n",
+                          now, now.millisecond());
+      auto state_timer = timer {{status_checker, &timer_example::status_checker::check_status},
+                                auto_event, 1000, 250};
+      
+      // When auto_event signals, change the period to every half second.
+      auto_event.wait_one();
+      state_timer.change(0, 500);
+      console::write_line("\nChanging period to .5 seconds.\n");
+      
+      // When auto_event signals the second time, dispose of the timer.
+      auto_event.wait_one();
+      state_timer.close();
+      console::write_line("\nDestroying timer.");
+    }
+  };
+}
+
+startup_(timer_example::program);
+
+// This example produces output similar to the following:
+//
+// 08:45:24.070 Creating timer.
+//
+// 08:45:25.076 Checking status  1.
+// 08:45:25.333 Checking status  2.
+// 08:45:25.591 Checking status  3.
+// 08:45:25.847 Checking status  4.
+// 08:45:26.101 Checking status  5.
+// 08:45:26.365 Checking status  6.
+// 08:45:26.611 Checking status  7.
+// 08:45:26.864 Checking status  8.
+// 08:45:27.118 Checking status  9.
+// 08:45:27.375 Checking status 10.
+//
+// Changing period to .5 seconds.
+//
+// 08:45:27.885 Checking status  1.
+// 08:45:28.389 Checking status  2.
+// 08:45:28.897 Checking status  3.
+// 08:45:29.402 Checking status  4.
+// 08:45:29.913 Checking status  5.
+// 08:45:30.414 Checking status  6.
+// 08:45:30.922 Checking status  7.
+// 08:45:31.428 Checking status  8.
+// 08:45:31.934 Checking status  9.
+// 08:45:32.445 Checking status 10.
+//
+// Destroying timer.