Context is a Search API query parameter that can be used to include custom data in a query, which can be leveraged in Coveo query pipeline conditions and can also provide Coveo Machine Learning models with specific contextual information about the current query so they can output more personalized suggestions. When context data is included in a query, the customData field of the corresponding Search usage analytics event is typically populated with equivalent information to allow Coveo Machine Learning models to learn from that logged data.