A trade mark registration:
Registered trade marks give much better rights than company names, business names and domain names, for example. Company names, business names and domain name registrations do not give you exclusive rights to the name and there is nothing stopping others from registering or using even very similar company names, business names and domain names. Only a trade mark can help with this.
If you generate a reputation in a trade mark (through extensive use/sales in connection with the trade mark) the business will accrue rights in that trade mark that can be enforced against others. These are called common law rights, or unregistered rights. However, registering a trade mark gives more formal recognition to the trade mark (regardless of reputation) and gives the owner many practical benefits over and above unregistered rights to a trade mark.
For example, say you sell toys under the name RAINBOCORNS and a competitor uses your trade mark as a Google Adword and displays RAINBOCORNS in the adtext when people search for your product by the name RAINBOCORNS. If you have a trade mark registration for RAINBOCORNS then you can use the Google complaint process to stop the competitor doing this. But if you do not have a trade mark registration then this situation would be much more difficult (and costly) to deal with. You can do similar things if someone misuses your brand on social media pages, or in a domain name.
Here is another example to explain the geographical benefits of a trade mark registration. Say you have a successful car washing business in Auckland and someone starts up another car washing business in Wellington under the same name. If you have a trade mark registration for your business name then you would have trade mark infringement grounds to stop them trading under the name. If you do not have a trade mark registration then you would need to prove that you have a reputation in the name such that people would think that the other business is your business, or that you are somehow connected (like a franchise), and this can be a difficult task. This could be a problem for you if you have plans to expand, or if the other business does poor work and this could reflect badly on your business.
In short, registering a trade mark gives you an asset and stronger rights than an unregistered trade mark, and company names and domain names. It is usually a straightforward process to register a trade mark (assuming it qualifies as a trade mark and is not similar to other trade marks) and well worth your while.
Trade mark registration process