Spambots are computer programs that scour the Internet looking for email addresses. These are fed back to a central database that is then used to send huge volumes of spam emails. Spam now accounts for over 50% of email traffic. The main way to prevent them getting your email address is to make sure it doesn't appear on the Internet.
A low-tech way of hiding your address is writing it out without the "@" symbol. So you could write your address as:
joebloggs (at) mywebsite (dot) com
Most human visitors will know what this means, but it will be enough to fool many pieces of software. However some advanced programs maybe programmed to specifically look for this pattern.
If your email address needs to appear on a website, another approach is to use a script. This scrambles the address so that it is not visible to a spam bot but it appears normally on the page if a human was to view it.
A better solution is to use a form on your webpage to replace a simple email address. This can then be set up to send the contents of the form to your email address. This also has the advantage that you can ask the user for specific information by putting a required field onto the form.
Employing either of these measures should reduce the chance of your email address being harvested by spam bots. You should combine this with common sense practices like not revealing your email address on public forums or bulletin boards that can be easily crawled by email harvesting software.