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Chapter 4 Building an OWL Ontology 
 
This chapter describes how to create an ontology of Pizzas. We use Pizzas because it is something almost 
everyone is familiar with.  
Exercise 1: Create a new OWL Ontology 
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1. Start Protégé.  When Protégé opens for the first time each day it puts up a screen of all the available 
plugins. You can also bring this up at any time by using File>Check for plugins. You won’t need any 
plugins at this point of the tutorial so just click the Not now button.  
2. The Protégé user-interface consists of several tabs such as Active ontology, Entities, etc. When you 
start Protégé you should be in the Active Ontology tab. This is for overview information about the entire 
ontology. Protégé always opens with a new untitled ontology you can start with. Your ontology should 
have an IRI something like: http://www.semanticweb.org/yourname/ontologies/2020/4/untitled-ontology-
27 Edit the name of the ontology (the part after the last “/” in this case untitled-ontology-27) and change it 
to something like PizzaTutorial. Note: the Pizza ontology IRIs shown below (e.g., figure 4.3) show the 
IRI after I edited the default that Protégé generated for me. Your IRI will look different and will be based 
on your name or the name of your organization.  
3. Now you want to save your new ontology. Select File>Save. This should bring up a window that says: 
Choose a format to use when saving the ‘PizzaTutorial’ ontology. There is a drop down menu of formats 
to use. The default RDF/XML Syntax should be selected by clicking the OK button. This should bring up 
the standard dialog your operating system uses for saving files. Navigate to the folder you want to use and 
then type in the file name, something like Pizza Tutorial and select Save. 
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The next step is to set some preferences related to the names of new entities. Remember than in Protégé 
any class, individual, object property, data property, annotation property, or rule is referred to as an entity. 
The term name in OWL can actually refer to two different concepts. It can be the last part of the IRI3 or it 
can refer to the annotation property (usually rdfs:label) used to provide a more user friendly name for 
the entity. We will discuss this in more detail below in chapter 7.  For now, we just want to set the 
parameters correctly so that future parts of the tutorial (especially the section on SPARQL queries) will 
work appropriately.  
 
 
 
3 An IRI is similar to a URL. This will be discussed in detail below in chapter 7.  
As with any file you work on it is a good idea to save your work at regular intervals so that if 
something goes wrong you don’t lose your work.  At certain points in the tutorial where saving 
is especially important the tutorial will prompt you to do so but it is a good idea to save your 
work often, not just when prompted.