Organic traffic is getting ranked in Google's listings that do not require any ad spend, meaning when you get clicked on by someone searching for your company or the services you provide it doesn't cost you any money for that click.

Paid ads are when you are charged usually every time someone clicks on your ad (Pay-Per-Click). This can be changed and charged based on conversions but that's a conversation for another day.

Related Article: 'Will I Rank Ahead Of My Competitors?'

Statistical data tells us that users prefer organic rankings as they convert higher (2-3 times) than paid adverts do, however, as you have found out from the question "How long does SEO take " it takes time to get those rankings, whereas paid ads can go live and get found on the first page usually the same day you set your campaign live.

To get a visual understanding of this, go to Google.com and type in the word "solicitors".

The first 4 listings will have a little "ad" next to them on the left, if you scroll further down, usually past the maps and some questions that might be there, you will see a different bunch of listings (10 in total) that do not have the word ad next to them - these are organic listings which are part of SEO, then followed by another 3 listings which also have"ad" next to them.