With the reintroduction of the Start menu, the ability to search is also available in the Start menu again, as it was in Windows 7. To search simply press the Windows button and type the name of the item you're looking for:
The search results will include programs, apps and files on your PC as well as suggested searches to be performed using Bing.
Slightly puzzling, bearing in mind the ability to search on the Start menu, there is also a separate Search app pinned to the task bar next to the Start button:
This works in almost the same way as the search on the Start menu, but without the explicit link to Bing at the bottom.
While I will be removing this app and only searching from the Start menu, I assume the purpose of the Search app is because there are users who do not realise you can search from the Start menu.