Handlebars templates are strings interpolated by JavaScript functions. When the function comes across double curlies, it tries to resolve the instance of the delimiter with an object property or invoke a nested function to return a string. These nested functions are called helpers and are created in the application. There are a few helpers built into the Handlebars library, and Ember adds some of its own.

Helpers can take two forms. The first are inline helpers, which use the syntax {{[helper name] [arguments]}}. The arguments can include a hash of options, such as:

{{input type="text" value=firstName disabled=entryNotAllowed size="50"}}

More complex helpers use a block syntax:

{{#[helper name] [arguments]}} [block content] ...

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