Ensuring that each existing article type has a corresponding Salesforce Knowledge article type that matches its structure and content is a factor that a consultant should consider as part of the migration strategy for Knowledge articles. An article type is a template that defines the layout, fields, and data categories for an article. An article type can be customized to suit different types of content or audiences. When migrating articles from an external database to Salesforce Knowledge, it is important to ensure that there is a matching article type for each existing article type in Salesforce Knowledge, so that the articles can be imported without losing any information or formatting. Verified References: Service Cloud Consultant Certification Guide & Tips, Article Types Overview