A CDN is a Content Delivery Network. Cloudflare is the most popular and common tool used for this. CDN’s make a copy of your website and store it in many different countries so the visitors from that country can be served your content faster.
Instead of fetching it from your server in Australia, it is delivered from the CDN in the UK. This speeds up your website by reducing the server load. It also has a less well known advantage – It reduces hacking success because the hacker is served a ‘shadow’ of your site not the real thing from your server. Hard to hack a shadow!
Most CDN’s allow targetting. This allows you to provide your target market with content faster and more effectively. They also provide geo-blocking, which allows you to deny visitor requests fom any country you choose – a very useful tool in the war against hackers and malware.
Using a CDN has reduced hacking attempts massively, though unfortunately, one of the top 4 countries for hacking is the USA, so it’s hard to prevent completely if you sell into that market.