This tag was originally used to identify mobile content in Blackberry and AvantGo browsers (on Palm devices), but became a general standard for identifying mobile websites. However, the marketshare for Blackberry and Palm has dropped significantly and it is doubtful that any modern browsers support this meta tag.
<meta name=”HandheldFriendly” content=”true”/>
There are many files that crawlers expect to find in well-known locations on websites, one such file is ads.txt. While you might not have paid advertisements, crawlers may still look for a copy of this file leading to HTTP 404 errors in your logs. To prevent the error and show that you should have no advertisements leading there you can add the file with placeholder values as follows:
In the root of your website, create a new file with the name ads.txt.
#ads.txt - no DIRECT or RESELLER
www.example.com, placeholder, DIRECT, placeholder
NOTE: If you ever do use an advertiser, they will generally inform you as to changes to make to this file.