Coding a search engine requires a variety of skills and technologies, depending on the complexity of the search engine and its performance requirements. Generally, search engine development involves three main components: indexing, document processing and query processing.

Indexing is the process of creating an index of web documents or other text sources so that keywords can be quickly retrieved. Indexing involves constructing an inverted index, a data structure which maps terms (words or phrases) to documents that contain that term. Popular algorithms for indexing include TF-IDF and BM25.

Document processing involves processing the content of web documents and other text sources. Processing includes tasks such as stop word filtering, part-of-speech tagging and stemming, which help increase the precision of the search engine results.

Query processing identifies the relevant documents to a user query, by reading through the index. Popular algorithms for query processing include vector space and language models.

Search engines are usually built using programming languages such as Java, C# or Python. Web frameworks and libraries such as Apache Solr or Lucene can help with developing a search engine. Additionally, there are a variety of off-the-shelf search engines such as Elasticsearch and Endeca.