Hi Marie,
As described here, I have not included it on purpose.
I’ll quote:
Google and many other Search Engines have disbanded keywords, for many reasons. [One of those is because they’re regarded as spam.]
So it’s unnecessary to add those. I will of course add them when they’re required for SEO again.
More information regarding the tags that Google understands is found right here.
More in-depth information about why they disbanded keywords is found in this lovely video by Matt Cutts:
https://www.youtube.com/watch?v=jK7IPbnmvVU
I hope this clears things up! Let me know if you have any more questions! 🙂
