It's part of a new tag add on installed a couple of days ago. It's designed to help manage the tags, stop duplicates such as courgette, courgettes, zucchini and heaven forbid zucchinis (not to mention spelling mistakes), along with allowing me to see how created a tag much more easily (fit instance if something inappropriate where to be made) and actually automatically tag things if the tag already exists. As you have noticed, you can still edit the tags, but it will help me because most of the tags you see have either been added by yourself or me.
It should prove really useful because of a title is "aubergine, broccoli and peanut soup" then given that aubergine, broccoli, peanut and soup already exist as tags, they will automatically get added. It also stops peanut being created and adds peanuts in because the tags are very specific. Peanut is not the same as the plural peanuts and they are certainly not groundnuts or groundnut as far as tags are concerned. With this new add on and a little programming by me, all 4 will end up under the same tag of peanuts so the imaginary soup would be found even if you were to search on groundnut.
I'm in the process of writing up the information/help regarding the tags but needed to learn the add on first. Hopefully I will have the help updated by weekend.
