Center a single marker

{exp:gmaps:init}

{exp:channel:entries limit="1"}
    {exp:gmaps:map width="100%" center:latlng="{gmaps_fieldtype_field:marker:n:latlng}" zoom="15"}
{/exp:channel:entries}

Channel Form

{exp:channel:form id="gmaps_fieldtype_channel_form" channel="gmaps_fieldtype" return="gmaps/channel-form" include_assets="yes"}
   <input name="title" type="text">
   <input name="url_title" type="text">

   {field:gmaps_fieldtype}

   <input type="submit" value="Submit">
{/exp:channel:form}

Example Zoom

{exp:gmaps:init}
{exp:channel:entries entry_id="351"}
   {gmaps_fieldtype zoom="12"}
{/exp:channel:entries}

Has marker check (conditional)

{exp:gmaps:init}

{exp:channel:entries limit="1"}
    {gmaps_field_extension:has:markers}
        ...
    {/gmaps_field_extension:has:markers}
{/exp:channel:entries}

Marker loop with add_marker tag

{exp:gmaps:init}

{exp:channel:entries entry_id="3" dynamic="no"}
    {exp:gmaps:map fit_map="markers"}
      {gmaps_fieldtype:markers}
          {add_marker}
      {/gmaps_fieldtype:markers}
    {/exp:gmaps:map}
{/exp:channel:entries}

or with extra params

{exp:gmaps:init}

{exp:channel:entries entry_id="3" dynamic="no"}
    {exp:gmaps:map fit_map="markers"}
      {gmaps_fieldtype:markers}
          {add_marker animation="yes"}
      {/gmaps_fieldtype:markers}
    {/exp:gmaps:map}
{/exp:channel:entries}

or from a bunch of entries

{exp:gmaps:init}
{exp:gmaps:map fit_map="markers"}
    {exp:channel:entries dynamic="no"}
      {gmaps_fieldtype:markers}
          {!-- map_id is needed due the parse order of EE --} 
          {add_marker animation="yes" map_id="{map_id}"} 
      {/gmaps_fieldtype:markers}
    {/exp:channel:entries}
{/exp:gmaps:map}

Marker loop

{exp:gmaps:init}
{exp:channel:entries entry_id="351"}
   <ul>
   {gmaps_fieldtype:markers}
      <li>{title} : {lat},{lng}</li>
   {/gmaps_fieldtype:markers}
   </ul>
{/exp:channel:entries}

Route based on the makers

{exp:gmaps:init}
{exp:gmaps:map
    width="100%"
    fit_map="route"
}
    {gmaps:add_route
        address:from="{your_custom_gmaps_field:route:from}"
        address:to="{your_custom_gmaps_field:route:to}"
        address:stops="{your_custom_gmaps_field:route:stops}"
    }
{/exp:gmaps:map}

Simple Example

{exp:gmaps:init}
{exp:channel:entries entry_id="351"}
   {gmaps_fieldtype}
{/exp:channel:entries}