The page title appender in Plug in SEO Plus works automatically for every page on your shop to make sure that you're getting the most out of your page titles for SEO ranking when they would normally be too short.
How it works
Say, for example, you have a 'T-shirts' collection. The page title would be 'T-shirts': too short because it doesn't fill the 65+ characters that search engines will display and only has one keyword in there for ranking.
On the other hand, say we have a collection 'Autumn/Winter 100% cotton Stock Photo T-shirts for men': a good length, filling the space search engines will display and containing a few good keywords for ranking.
The appender feature works by automatically appending to the page title (adding to the end of the page title) when it is too short.
So if we set up the appender as ' | 100% cotton Stock Photo T-shirts for men' and a target length of 70, this will be appended to too short page titles.
In our example the appender would change the 'T-shirts' page title to 'T-shirts | 100% cotton Stock Photo T-shirts for men': taking full advantage of the search engine display space and ranking opportunity.
The appender wouldn't change 'Autumn/Winter 100% cotton Stock Photo T-shirts for men' because adding ' | 100% cotton Stock Photo T-shirts for men' would take it over 70 characters in length.
This is good for SEO because it extends short page titles but leaves page titles that are already a decent length alone.
More Information: How do I setup my page title appender?