github.com/npaton/distribution@v2.3.1-rc.0+incompatible/docs/glossary.md (about)

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     7  # Glossary
     8  
     9  This page contains definitions for distribution related terms.
    10  
    11  <dl>
    12  	<dt id="blob"><h4>Blob</h4></dt>
    13  	<dd>
    14        <blockquote>A blob is any kind of content that is stored by a Registry under a content-addressable identifier (a "digest").</blockquote>
    15        <p>
    16        	<a href="#layer">Layers</a> are a good example of "blobs".
    17        </p>
    18  	</dd>
    19  
    20  	<dt id="image"><h4>Image</h4></dt>
    21  	<dd>
    22        <blockquote>An image is a named set of immutable data from which a Docker container can be created.</blockquote>
    23        <p>
    24        An image is represented by a json file called a <a href="#manifest">manifest</a>, and is conceptually a set of <a hred="#layer">layers</a>.
    25  
    26        Image names indicate the location where they can be pulled from and pushed to, as they usually start with a <a href="#registry">registry</a> domain name and port.
    27  
    28        </p>
    29      </dd>
    30  
    31  	<dt id="layer"><h4>Layer</h4></dt>
    32  	<dd>
    33  	<blockquote>A layer is a tar archive bundling partial content from a filesystem.</blockquote>
    34  	<p>
    35  	Layers from an <a href="#image">image</a> are usually extracted in order on top of each other to make up a root filesystem from which containers run out.
    36  	</p>
    37  	</dd>
    38  
    39  	<dt id="manifest"><h4>Manifest</h4></dt>
    40  	<dd><blockquote>A manifest is the JSON representation of an image.</blockquote></dd>
    41  
    42  	<dt id="namespace"><h4>Namespace</h4></dt>
    43  	<dd><blockquote>A namespace is a collection of repositories with a common name prefix.</blockquote>
    44  	<p>
    45  	The namespace with an empty prefix is considered the Global Namespace.
    46  	</p>
    47  	</dd>
    48  
    49  	<dt id="registry"><h4>Registry</h4></dt>
    50  	<dd><blockquote>A registry is a service that let you store and deliver <a href="#images">images</a>.</blockquote>
    51  	</dd>
    52  
    53  	<dt id="registry"><h4>Repository</h4></dt>
    54  	<dd>
    55  	<blockquote>A repository is a set of data containing all versions of a given image.</blockquote>
    56  	</dd>
    57  
    58  	<dt id="scope"><h4>Scope</h4></dt>
    59  	<dd><blockquote>A scope is the portion of a namespace onto which a given authorization token is granted.</blockquote></dd>
    60  
    61  	<dt id="tag"><h4>Tag</h4></dt>
    62  	<dd><blockquote>A tag is conceptually a "version" of a <a href="#image">named image</a>.</blockquote>
    63  	<p>
    64  	Example: `docker pull myimage:latest` instructs docker to pull the image "myimage" in version "latest".
    65  	</p>
    66  	
    67  	</dd>
    68  	
    69  
    70  </dl>