diff --git a/core/modules/migrate/src/Plugin/migrate/process/Get.php b/core/modules/migrate/src/Plugin/migrate/process/Get.php
index f6b3c34..16ee2a8 100644
--- a/core/modules/migrate/src/Plugin/migrate/process/Get.php
+++ b/core/modules/migrate/src/Plugin/migrate/process/Get.php
@@ -7,9 +7,74 @@
 use Drupal\migrate\Row;
 
 /**
- * This plugin copies from the source to the destination.
+ * Gets the source value.
  *
- * @link https://www.drupal.org/node/2135307 Online handbook documentation for get process plugin @endlink
+ * Typically, the get plugin is the start of every process pipeline, typically
+ * shorthanded by adding a source key to another plugin.
+ *
+ * It has a single configuration key, the source. The value typically is a
+ * source property and after running this plugin, the pipeline value will be set
+ * to the value of that property.
+ *
+ * Available configuration keys
+ *   - source: Source property.
+ *
+ * Examples:
+ *
+ * @code
+ * process:
+ *   bar:
+ *     plugin: get
+ *     source: foo
+ * @endcode
+ *
+ * This copies the source value of foo to the destination property bar. Since
+ * get is the default process plugin, it can be shorthanded as such:
+ *
+ * @code
+ * process:
+ *   bar: foo
+ * @endcode
+ *
+ * get also supports a list of source properties. If this list contains an empty
+ * element then the current value will be used. This makes it impossible to
+ * reach a source property with an empty string as its name.
+ *
+ * get also supports copying destination values. These are indicated by a
+ * starting @ sign. Values using @ must be wrapped in quotes.
+ *
+ * @code
+ * process:
+ *   foo:
+ *     plugin: machine_name
+ *     source: baz
+ *   bar:
+ *     plugin: get
+ *   source: '@foo'
+ * @endcode
+ *
+ * This will simply copy the destination value of foo to the destination
+ * property bar. foo configuration is included for illustration purposes.
+ *
+ * Because of this, if your source or destination property actually starts with
+ * a @ you need to double those starting characters up. This means that if a
+ * destination property happens to start with a @ and you want to refer it,
+ * you'll need to start with three @ characters -- one to indicate the
+ * destination and two for escaping the real @.
+ *
+ * @code
+ * process:
+ * @foo:
+ *   plugin: machine_name
+ *   source: baz
+ * bar:
+ *   plugin: get
+ *   source: '@@@foo'
+ * @endcode
+ *
+ * This should occur extremely rarely.
+ *
+ * @see \Drupal\migrate\Plugin\MigrateProcessInterface
  *
  * @MigrateProcessPlugin(
  *   id = "get"