Spam is unsolicited email that you get in your inbox, usually attempting to sell you something or entice you to a website. This email can be annoying if it arrives en masse but some spam can also be malicious, attempting to phish information or install malware on your computer. Depending on your email provider, they will usually have a spam filter applied to your email, but these can be overcome if you signup for marketing emails, or your email address is added to a spam list.
One of the largest spam databases has been discovered recently, weighing in at a massive 14GB and approximately 711 million email addresses. Worryingly, some of these email addresses also included passwords. These are likely to have been harvested from hacked sites such as Yahoo. If you want to identify whether your email address is on the list then go to https://haveibeenpwned.com/ and check there. If you do find your email listed, then it is a good idea to change the passwords associated with that email address so that hackers don't use those details to gain access to your information.
The other issues with being on the spam list is that you are likely to get more spam emails. Once your email is added to a spam list it is difficult to remove it. While legitimate companies will provide an unsubscribe feature, this can be used by illegitimate spammers to confirm that your email address is active. So once you click on the unsubscribe link, you will be targeted for further emails. As mentioned earlier, depending on your email provider, the spam protection may vary. The larger email providers like GMail and Outlook.com allow you to identify spam in your inbox, and this helps fine tune the settings for your email. Bigpond don't have the same level of protection so you will need to use a client based spam filter to fine tune the spam settings. Spamfigher (http://www.spamfighter.com/) is a paid product with a free ad supported version, that can be added to the common email clients (Outlook, Windows Mail etc.) to provide additional spam protection if required. Some anti-virus products will also include spam protection as part of the security suite.
Often the best way to beat spam is to avoid it. To prevent your email address being used for spam, use a separate junk email address for signing up to sites or marketing lists. This way you can check the junk email occasionally for any legitimate email but keep your private email safe from spam. For more information on tuning your spam filter in gmail and outlook.com, take a look at these sites.