"node-red-contrib" means as custom node or library?


"node-red-contrib" means as custom node or library. As i can see in the manage palette there is more than thousands of npm library. so what i see there some library name starting with "node-red-contrib..." and some of them without "contrib". I know node modules should use node-red-contrib- as a prefix to their name to make it clear they are not maintained by the Node-RED project.
#I am new in nodered so please let me know


So all majority of Nodes available for Node-RED are listed on
https://flows.nodered.org/?type=node&num_pages=1 (currently about 1660) and should be the same list as you see in "manage palette"

If the name starts with Node-red-node it was generally written by the core Node-RED team as part of their work on Node-RED
The majority of other nodes start with Node-red-contrib and as you mentioned are not maintained by the Node-RED project, as documented https://nodered.org/docs/creating-nodes/packaging.

The list on npmjs contains a lot of javascript libraries and code, but these cannot be used out-of-the-box with Node-RED. Which is why within npmjs you should look for the Node-RED keyword.

Does that answer your question?