How To: Apply Entity Linking Using the Highlighter

Entity linking is the process of identifying entities mentioned in your content and connecting them to unique entities in a knowledge graph. By linking content to known entities, you provide search engines and AI systems with additional context that helps them understand what your content is about and how it relates to other concepts.

With the Schema App Highlighter, entity linking can be applied to connect content to entities from external knowledge graphs such as Google's Knowledge Graph, Wikipedia, and Wikidata, as well as entities within your organization's internal knowledge graph. This helps create more meaningful structured data and strengthens the relationships between your content and the entities it references.

After reading this article, you will understand what entity linking is, how it differs from Named Entity Recognition (NER), when to use each knowledge graph source option, and how to apply entity linking using Schema App Highlighter.

Optional: Pre-Requisites

• Access to Schema App Highlighter
• An existing Highlighter template or permission to create a new template
• Content containing references to entities such as organizations, people, products, places, or topics

Audience

• Schema App Highlighter users
• SEO practitioners
• Content strategists
• Knowledge graph managers

Note: Entity linking works best when the content contains clearly identifiable entities that can be associated with an external or internal knowledge graph.

Context, Required Knowledge, & Why This Article?

Schema App Highlighter includes Linked Entity Recognition functionality that can automatically identify entities within your content and connect them to known entities in a knowledge graph. This allows you to enrich your structured data without manually researching and linking every entity.

Before using this feature, it is helpful to understand how entity linking works, how Named Entity Recognition (NER) is used during the process, and which knowledge graph source is most appropriate for your use case.

Problem & Objectives

Problem: Users often want to enrich their structured data with entity references but may not know how entities are identified or which knowledge graph source should be used.

Objective: Learn how Linked Entity Recognition works in Highlighter, understand the differences between available knowledge graph sources, and configure entity linking within a template.

Understanding Entity Linking and Linked Entity Recognition

Entity linking is the process of connecting text in your content to a specific entity in a knowledge graph. For example, the text "Apple" could refer to a company, a fruit, or a record label. Entity linking attempts to identify the correct entity and associate the content with a unique identifier.

What is Named Entity Recognition (NER)?

Named Entity Recognition (NER) is the process of identifying potential entities within content. NER determines which words or phrases may represent people, organizations, locations, products, events, or other entities.

After NER identifies candidate entities, entity linking attempts to match those entities to entries in a knowledge graph.

How Does Entity Linking Improve Structured Data?

Entity linking adds semantic context to your markup by establishing relationships between your content and known entities. This can help search engines and AI systems better understand the meaning of your content and how it relates to other entities across the web.

How To: Apply Entity Linking Using the Highlighter

Step 1: Create a Linked Entity Recognition tag

1. Open an existing Highlighter template or create a new template.
2. Select an existing property or create a new property where linked entities should be applied.
3. Open the property settings, and click Apply Linked Entity Recognition.
4. Select an are on your webpage where you'd like to apply Linked Entity Recognition
5. Once results are retrieved, click any entity's source hyperlink to review the contents of that source

Step 2: (Optional) Configure your Knowledge Graph Source

Choose which data source the Highlighter should search for matching entities.

1. External Knowledge Graph

The External Knowledge Graph is the default source option. It searches publicly available knowledge sources such as Google's Knowledge Graph, Wikipedia, and Wikidata.

This option is best when:

• Your content references well-known public entities.
• The entities you want to reference are unlikely to exist in your internal knowledge graph.

2. Internal Knowledge Graph

The Internal Knowledge Graph option searches entities that exist within your organization's knowledge graph.

This option is best when:

• You want to strengthen relationships between your own entities.
• The entities being referenced are not represented in public knowledge graphs.

Consideration: When using the Internal Knowledge Graph source, you can enable Exact Match Text Only to exclusively link to entities whose labels exactly match the selected text. This is useful when you want highly controlled matching behavior.

3. All Knowledge Graphs

The All Knowledge Graphs option searches both external knowledge graphs and your internal knowledge graph.

This option is best when:

• You want the broadest possible entity coverage.
• Your content references a mixture of public and proprietary entities.
• You are unsure where matching entities are likely to exist.

Step 3: (Optional) Restrict Type of Results

Entity Linking tags can be created for entities of any type, entities of a specific type, or entities of a specific type + subtypes.

Type restrictions can be added

Consideration: Use the Schema Paths Tool or look at the schema.org type documentation to identify which property to use to connect your entity linking results to your template markup.

1. Any Type

If you expect to receive entities of any type, you must use a property that expects schema.org/Thing so that entities of any type can be added to your content.

• Example 1: if applying to the article body of a BlogPosting, use the mentions or about property to capture entities of any type.
• Example 2: if applying to the "areas of expertise" of a Person's profile page, use the knowsAbout property to capture entities of any type.

2. Specific Type Only
You can also restrict the entity linking results to a specific type in order to use more specific properties.

• Example 1: if you want to say a Service has an areaServed, restrict results to the Place type.
• Example 2: if you want to say a Product if from a brand, restrict results to the Organization type.

3. Specific Type + Subtypes
By selecting "Search within subtypes" to your Type restriction, it can be extended to also accept entities of any of the subtypes of the specified type. 

• Example 1: if you want to link to entities that are types as Organization and/or LocalBusiness, restrict results to the Organization type and select "Search within subtypes". 

Step 4: Review and Validate Entity Linking Results

After saving the template, allow the Entity Linking process time to identify and link entities across eligible pages. 

While you can validate individual URLs using the Schema Validator, we recommend reviewing the results using Entity Reports. Entity Reports provide a holistic view of all entities identified across all URLs where the Highlighter template has been applied, making it easier to evaluate entity linking performance at scale.

1. Save the Highlighter template.
2. Allow the template to deploy and process eligible pages.
3. Use the Schema Validator to spot-check individual URLs if needed.
4. Review the Entity Reports to evaluate entities identified across your site.
5. Confirm that identified entities accurately represent the content on your pages.

Note: Entity linking results may not appear immediately across all pages. Depending on the number of pages being processed and deployment method, it may take time for all eligible entities to be identified and linked.

Reviewing Results on Individual URLs

The Schema Validator can be used to verify that linked entities are appearing in the structured data for a specific URL. This is useful when testing a newly configured template or troubleshooting a particular page.

External Entity	Internal Entity
Has a type and a name @id begins with https://entity Contains sameAs relationships to Wikidata, Wikipedia, and/or Google's Knowledge Graph	Has a type and a name @id is the website URL that represents the entity Contains an identifier property stating the entity is from an internal source

Reviewing Results Across Your Site

Entity Reports provide a consolidated view of the entities identified by Entity Linking across all URLs where the template has been applied. These reports can help you:

• Understand which entities are being identified most frequently.
• Verify that expected entities are being linked across your content.
• Identify incorrect or unexpected entity matches.
• Evaluate the overall quality of entity linking results.

For more information, see our Entity Reports documentation.

Managing Incorrect Entity Matches

If you identify entities that have been linked incorrectly, you can use the Entity Manager tool to review, modify, or block those entities.

Common reasons to update or block an entity include:

• The wrong entity was selected for an ambiguous term or phrase.
• An entity is not relevant to your content.
• You want to prevent a specific entity from being identified in future runs.
• You want to associate the content with a different entity.

For more information, see our Entity Manager documentation.

Troubleshooting Missing or Unexpected Results

If expected entities do not appear, consider the following:

• The content may not contain recognizable entity references.
• The entity may not exist in the selected knowledge graph source.
• The selected property may not be appropriate for the identified entity type.
• If using Exact Match Text Only, the entity label may not exactly match the text found on the page.
• Recently configured entity linking may require additional time before all eligible pages have been processed.

Conclusion

Entity linking helps enrich structured data by connecting content to known entities in a knowledge graph. By understanding how Linked Entity Recognition works and selecting the appropriate source option, you can create more meaningful relationships between your content and the entities it references.

For most organizations, External Knowledge Graphs are useful for public entities, Internal Knowledge Graphs are useful for proprietary entities, and All Knowledge Graphs provide the most comprehensive coverage when both are important.