Introduction to Azure Search

Azure search is simply a cloud service which gives developers an API for rich search experience. It executes queries over a user-defined index.

Azue search supports,

• Search data from multiple content types and platforms
• AI powered indexing to extract text from image files or key phrases from raw text
• Create search experience with filters, synonyms, auto-complete and text analysis for "did you mean" auto correct search terms
• Geo-search for find near me.

Functionality is exposed over a REST API or .NET SDK.  

Azure search comes with following features

• Full text search and text analysis
• Cognitive search (in preview)
• Data integration
• Linguistic analysis
• Geo-search
• User experience features
• Relevance
• Monitoring and reporting
• Tools and prototyping and inspection
• Infrastructure

Steps to use

• Provision service
• Create index
• Load Data
• Search

Indexer

Indexer is a crawler that extracts searchable data and metadata from a external Azure data source and populate index based on field-to-field mapping between indexer and data source.

Connecting Azure Search with Azure SQL Database
https://docs.microsoft.com/en-us/azure/search/search-howto-connecting-azure-sql-database-to-azure-search-using-indexers