These charts represent the "popularity coefficient" of the different programming languages and technologies (frameworks, libraries, software...) based on StackOverflow's activity (tags, questions, answers & votes).
What is the grey region at the end of every chart?
The grey region represents the trending prediction for languages and technologies. This prediction is based on a polynomial regression algorithm. The rest of the data reflects the real activity.
Why is the current month within the prediction region?
These charts are calculated from the public StackOverflow's dataset, which is released every 3-4 months (read more in the About section). This website's data cannot be updated until the next dataset is released.