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mapped_pages:
  - https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-charfilters.html
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# Character filter reference [analysis-charfilters]

*Character filters* are used to preprocess the stream of characters before it is passed to the [tokenizer](/reference/text-analysis/tokenizer-reference.md).

A character filter receives the original text as a stream of characters and can transform the stream by adding, removing, or changing characters. For instance, a character filter could be used to convert Hindu-Arabic numerals (٠‎١٢٣٤٥٦٧٨‎٩‎) into their Arabic-Latin equivalents (0123456789), or to strip HTML elements like `<b>` from the stream.

Elasticsearch has a number of built in character filters which can be used to build [custom analyzers](docs-content://manage-data/data-store/text-analysis/create-custom-analyzer.md).

[HTML Strip Character Filter](/reference/text-analysis/analysis-htmlstrip-charfilter.md)
:   The `html_strip` character filter strips out HTML elements like `<b>` and decodes HTML entities like `&amp;`.

[Mapping Character Filter](/reference/text-analysis/analysis-mapping-charfilter.md)
:   The `mapping` character filter replaces any occurrences of the specified strings with the specified replacements.

[Pattern Replace Character Filter](/reference/text-analysis/analysis-pattern-replace-charfilter.md)
:   The `pattern_replace` character filter replaces any characters matching a regular expression with the specified replacement.