diff --git a/docs/topics/settings.rst b/docs/topics/settings.rst
index 0515a9e0d..c1f488f73 100644
--- a/docs/topics/settings.rst
+++ b/docs/topics/settings.rst
@@ -827,13 +827,15 @@ Example::
 MEMUSAGE_ENABLED
 ----------------
 
-Default: ``False``
+Default: ``True``
 
 Scope: ``scrapy.extensions.memusage``
 
-Whether to enable the memory usage extension that will shutdown the Scrapy
-process when it exceeds a memory limit, and also notify by email when that
-happened.
+Whether to enable the memory usage extension. This extension keeps track of
+a peak memory used by the process (it writes it to stats). It can also
+optionally shutdown the Scrapy process when it exceeds a memory limit
+(see :setting:`MEMUSAGE_LIMIT_MB`), and notify by email when that happened
+(see :setting:`MEMUSAGE_NOTIFY_MAIL`).
 
 See :ref:`topics-extensions-ref-memusage`.
 
diff --git a/scrapy/settings/default_settings.py b/scrapy/settings/default_settings.py
index cb88bc2bf..2d01befbb 100644
--- a/scrapy/settings/default_settings.py
+++ b/scrapy/settings/default_settings.py
@@ -208,7 +208,7 @@ MEMDEBUG_ENABLED = False        # enable memory debugging
 MEMDEBUG_NOTIFY = []            # send memory debugging report by mail at engine shutdown
 
 MEMUSAGE_CHECK_INTERVAL_SECONDS = 60.0
-MEMUSAGE_ENABLED = False
+MEMUSAGE_ENABLED = True
 MEMUSAGE_LIMIT_MB = 0
 MEMUSAGE_NOTIFY_MAIL = []
 MEMUSAGE_REPORT = False