WMS (Web Map Service) is a standard protocol for serving georeferenced map images over the Internet that are generated by map servers using data from GIS databases. These maps or map data layers are mostly provided by government organizations or education institutions.

WMS can serve almost any type of map. Beginning with topographic maps, historic maps, satellite, and aerial images, cycling routes, town plans, ending with various data layers like cadastral maps, weather services, environmental layers, etc.

For more info, read this Wiki page. WMS maps are managed in the WMS tab of Locus map manager.

Locus Map offers a library of worldwide WMS sources where you can select or you can enter a direct URL to add any WMS source you wish to the app.

• open WMS tab in the Maps Manager
• tap in the lower right corner and select Add from library:
  
• Locus Map offers WMS sources available in your area according to your GPS location:
  
• to specify your selection, use fultext search:
  
• tap the selected source - it is added to the WMS tab:
  

• tap again and then Enter WMS link:
  
• enter the WMS source address, name or password (if necessary) and press OK
• the source is added to the WMS tab
• if you think other Locus users would appreciate your link too, please, ask us to add it to the public WMS library:
  
  We'll test the link and after its validation, it'll be added to the library.

Other Action menu items:

• Details - information about the source - provider, terms of use, contacts etc.
• Layers - available layers in the source
• Center map - aligns the map center with the cursor position in case your real location is outside the map
• Re-initialize - reloads required information from WMS server and sets the map to default values
• Disable - hides selected WMS layers in the map
• Remove - deletes the WMS source from the tab

• tap the selected WMS source in the map manager
• a list of available layers and an opacity slider appears:
  
• select layers to display, adjust their visibility above the active map and confirm.

After a WMS map is activated two new control buttons appear in the upper left corner:

• displays the opacity slider and active WMS layers list mentioned above - check or un-check layers to display or hide.
• displays a particular WMS feature information - aim the screen center at a WMS object on the map and tap the button. In case the object contains some additional information it displays in a pop-up window: