Windows 10 can gather up contacts, calendar details, text and touch input, and location data. The OS then sends it all back to Microsoft so that it can be used for personalisation and targeted ads. The easiest way to disable Windows 10’s various data logging, personalisation, and telemetry functions is to turn them off during the upgrade/installation process. If you’d rather keep Cortana turned on but with some of her other abilities curtailed, they can be configured here as well. Disabling personalisation makes sense from a privacy perspective, but it could dent accuracy of certain features like Cortana.”]