As you dig into your research topic, you may come across people, events, terms, and concepts that are foreign to you. While Wikipedia can be a good starting point for general information, it can also be a tricky source because you need to verify everything you read. See, for example, this article.
Rather than navigate the information landmine that is Wikipedia, rely on Oxford Reference. This is a giant database of all encyclopedias and dictionaries published by Oxford University Press. The entries have been researched and vetted by scholars so you can trust the information. Most entries also provide bibliography for further reading.
A few sources within the Oxford Reference library that will be useful for my classes include:
The Grove Encyclopedia of Classical Art and Architecture, ed. Gordon Campbell (Oxford, 2007).
The Grove Encyclopedia of Islamic Art and Architecture, eds. Jonathan M. Bloom and Sheila S. Blair (Oxford, 2009).
The Grove Encyclopedia of Materials and Techniques in Art, ed. Gerald Ward (Oxford, 2008).
The Oxford Classical Dictionary (4 ed.), eds. Simon Hornblower, Antony Spawforth, and Esther Eidinow (Oxford, 2012).
The Oxford Encyclopedia of Ancient Greece and Rome, ed. Michael Gagarin (Oxford, 2010).
The Oxford Dictionary of Byzantium, ed. Alexander P. Kazhdan (Oxford, 1991, 2005).