You can combine multiple keywords or concepts together in your search, using search operators, known as "Boolean connectors" or "Boolean operators". They are: AND, OR, and NOT.
Using connectors can improve the relevancy of your results, as the search engine or database will search your keywords in a more specific and filtered way.
In many databases, if you don't use a connector between your search words the AND connector automatically applies to your search.
For example, the keyword search: Brexit voting Wales would be interpreted as Brexit AND voting AND Wales.