Explain what "Cloudflare Worker" (or generally a Worker in the context of Cloudflare) exactly is, in very simple and casual language, as if you're explaining it to someone who's just seen the internet for the first time.

Please make sure to cover these points:

1. What's the main difference between a Worker and a regular server or normal hosting?
2. Why do they say it runs "on the edge of the network" or "edge"? What does that mean?
3. What can you do with it? (Give at least 7-8 real and practical examples, from simple stuff to things that are commonly used in Iran)
4. What are its main advantages compared to traditional servers (like VPS or shared hosting)?
5. What are its limitations? (For example, what can't you do with it?)
6. Roughly how long does it take to create and deploy a simple Worker? (For a beginner)
7. Is it really free, or does it have limits? What's the cost structure like?
8. In Iran, what is it mostly used for? (Like proxies, v2ray/xray panels, APIs, link shorteners, etc.)

Make your response complete, organized, and use headings/numbering so it's easy to read. Don't use very technical terms without explaining them. If needed, include a simple code example (like a hello world or a basic redirect).