What are RPC used for?

Can you explain what RPC stands for and the primary uses it serves in the cryptocurrency and finance realm? Are they critical for enabling specific functionalities, or are they merely supplementary tools? How do they impact the efficiency and security of transactions and communication within blockchain networks? Are there any industry-specific use cases where RPCs play a pivotal role? Understanding the fundamentals and practical applications of RPCs is crucial for anyone involved in the cryptocurrency and finance sector.