The visualize is great for troubleshooting data, identifying n-gons/triangles, uv texture distortion, and more.  To use a visualizer, you can either press tab and make a new visualizer node or use the hotkey 'x' while in sops.

Update Visualizers:

--  The visualize node will create a detail attribute called "visualizer," and this specifies any and all visualizers that have been applied to this geo stream.  If you turn this on, it tells the node to add this detail attribute with a path to the node.  If you leave this un-checked, then this information will not be appended to the list of visualizers.

Clear Incoming Visualizers:

--  If you're using multiple visualize nodes, then you can clear any entries within the visualizer detail atrribute which already exist by checking this on.

Wireframe:

--  The wireframe parameter overrides the display of wireframes in your viewport.  Force shaded will force the obj to be shaded - even if you hover over the viewport and press w.  Use viewport settings will do as it says.  Force wireframe will force a wireframe shading.

Lighting:

--  This provides lighting overrides.  Which allow you to preview something lit or unlit by the lights in your scene.

Show Points:

-   This highlights points on your object.  You can either select only the unconnected points (useful for troubleshooting un-connected points) or all points along the geo.

-  This provides an override for previewing normal smoothing in your viewport.  To keep things clean, I would advise against this parameter because it may interfere with normal smoothing that you may want to set later on in your network.  All of these attributes exist in the detail context, and this is where the viewport goes to pick up this information.  So, if you want to remove the "cusp angle" viewport override, then you'll want to delete the attribute in the detail context.

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Here you can add multiple visualizers to your viewport.  For more information about visualizer types in Houdini, please visit this link:  https://www.sidefx.com/docs/houdini/basics/visualizers.html#types
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Active:

--  Enables a visualizer

Name:

--  The name of the visualizer that is stored in the "visualizer" detail attribute

Label:

--  This is the human-readable name for this visualizer when it appears in the interface.

Type:

--  Marker
    *  For more information, visit:  https://www.sidefx.com/docs/houdini/visualizers/marker.html
    *  Can create text, element index, point trail, vector trail, vector, or axes 
    *  Text displays the value of an attribute
    *  Element Index displays the point number
    *  Point Trail draws a line from the element’s location to the point contained in an attribute value. For example, visualizing the contents of a rest attribute would draw lines from the current point positions to their rest positions.
    *  Vector trail draws a line from the point based on a vector attribute value’s direction and length.
    *  Vector is the same thing as vector trail except the direction of the line is inverted.  
    *  Axes Draws a small set of axes at each element to visualize a matrix or quaternion attribute.

        The attribute must have either:

        Nine (or more) components, in which case components 0-2, 3-5, and 6-8 are treated as the first, second, and third vector -- OR -- Four components, in which case it is treated as a quaternion.  For more information about the @orient attribute, please visit the copy to points node bible entry.

--  Color

    *  For more information, visit:  https://www.sidefx.com/docs/houdini/visualizers/color.html
    *  Colors your geometry in some way

        ** Attribute as is = The value of the attribute is equal to the output color values.  This only works properly with floating point attribute types. If the attribute has only one component, it is used as the red channel. If it has two components, they are used as red and green.

        **  Ramped Attribute = Will color the geo based on an attribute.  The difference here is that you can control the colors that are assigned to the in-between values of the attribute.  You need to specify a min/max range for this to work.  You can do so by choosing.....
              ***  Auto - which looks at the min/max values of the attribute and uses that as the min/max of the ramp
              ***  Min/Max - which allows you directly specify min/max values on the ramp
              ***  Center and Width - which allows you to specify the center value and how far away the min/max is from that center value.
      **  On the Ramped Attribute, "treat as scalar" will allow you to specify a specific component of the incoming data if it is a vec2, vec3, or vec4

      **  Constant = a constant color

      **  Random = a random color for each point/prim

      **  Random From Attribute = A random color whose seed is the attribute value.  As an example, if the attribute value = 200 on two points, then they would share the same random color.

      **  Polygon Vertex Count = Colors the primitives based on how many sides a polygon has.  Triangles are yellow, quads are gray, and n-gons are red by default.

      **  Texture Distortion = Tint faces based on how much the texture is being stretched or squashed in that area.
             ***  Measuring distortion globally is the default - which allows you to measure the distortion in size from one island to the next.  This is good to make sure that one island isn't too big compared to another island.  If you say local to each island, though, then it won't look at the scale of the other islands when determining distortion.  Finally, within polygons should be avoided unless you deem it necessary for some reason.  

--  Volume

    *  The volume visualizer is designed to preview volumes.  In general, it is advised to use other nodes when previewing volumes - specifically the volume visualization, volume slice, and volume trails SOPs because they are easier to control while attribute values are expressed in the geometry spreadsheet.  In addition, the visualize node will not show you values which exist within the volume because the volume preview blocks any values from being read in the viewport.  For this reason, it is best to refer to the other nodes when previewing volumes.

--  Tag

    *  Tags are useful for selecting and identifying things interactively within the viewport.  

    *  Note that tags only allow you to select objects on the obj level.  This will not include groups/faces/components of a geo network.

    *  The best way to familiarize yourself with the tag node options is by playing with them in the visualize node.  These settings are fairly straight-forward, but please refer to this video if you'd like further information.

    --  Constraints

        *  There is no documentation or settings for this parameter... so who knows?

    --  Capture Weights

        *  This is useful when rigging because it allows you to visualize the captured weights.  These weights can relate to one particular capture region or all captured regions.  Online documentation does not exist for these settings.

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This concludes the "Type" parameters
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Scope:

--   The scope determines which nodes this visualizer is allowed to apply to.  In practice, these parameter do not seem to work as intended.  If you want the visualization of something to transfer to its descendants, then it's best to use the "update visualizers" checkbox.  However, according to the user docs:

--  Node Only

    *  Only apply to the geometry generated by this node.

--  Same Network Type Descendants

    *  Apply to the geometry generated by this node, and (if it’s a network node) all the nodes inside the network that have the same network type.

--  All Descendants

    *  Apply to the geometry generated by this node, and (if it’s a network node) all the nodes inside the network.

--  Global

    *  Common and Scene visualizers display this setting and it can’t be changed.

At scene level/At geometry level:

--  Use the checkboxes to choose whether the visualizer applies to unselected, selected, and/or ghosted geometry.