Drop Catching in Australia
Australian domain names such as com.au and net.au domains are registered for a period of 2 years. if they are not renewed within this time, they go into an expired status. They will remain in this status for 30 days and the registrant will not be able to use the domain - it’s effectively a grace period giving the registrant a chance to renew the domain after all.
If they don’t renew - the domain is ‘purged’ from the registry and becomes available to register by any elligible entity. Sophisticated systems have been set up to catch or ’snap’ these domains as they become available as often some very vaulable domains can be left to expire.
If you want to find out how drop catching works, check out Netfleet’s Domain Snapper for more information. Also worth noting that you’ll find a full list of expiring domains at www.auda.org.au
Happy Domaining 
Domaining in a nutshell
So what is domaining?  Well, in a nutshell is the business of buying domain names and selling domain names with the intention of selling on at a later date for a profit. Simple!
Domainers will typically hold a portfolio of domain names, often that run in to the thousands, hoping for that elusive end user buyer. Its often a numbers game, with 95% of a domainers portfolio propping up the rest, funding domain name renewals, new domain name registrations or new aftermarket purchases.
Domaining also involves profiting from a domain name during ownership - known as monetising (or monetizing if you’re from that part of the world). That is to say, Mr X and his $10,000 might not appear for a few months, so in the meantime a domainer may park a domain name (a template website full of advertisements), build a small mini site with affiliate adverts, lease a domain name or develop a domain name to a fully functioning website so to increase resale value.