How do nodes fetch unconfirmed transactions?

I'm taking up a project to build a software in python to mine cryptocurrency (preferably bitcoin). I have an overview of the computation that needs to be done.

I would like to know how nodes fetch unconfirmed transactions.

In brief you would use your Bitcoin libraries functions to perform peer discovery and then periodically communicate with a few peers to collect data.

Your question isn't an exact duplicate of any question I can find but existing answers to the following questions will help:

• How transaction happen in blockchain?
• How do Bitcoin clients find each other?
• How are transactions broadcast to the rest of the network?
• How does a node get information from other nodes?

Other useful resources

• https://en.bitcoin.it/wiki/Protocol_documentation
• https://developer.bitcoin.org/devguide/p2p_network.html
  This covers the following topics
  • Peer discovery
  • Connecting to peers
  • Initial Block download
  • Block broadcasting
  • Transaction broadcasting
    This is the part where your node listens for inv messages and issues corresponding messages such as getdata.