The DEX allows you to buy, sell or exchange every asset existing within the Waves Platform.
The Waves Platform allows everyone to issue his very own custom blockchain token in literally two clicks.
As you can see in the Waves Lite Client, some of the Assets are accompanied by a green mark next to their name. Custom blockchain tokens with a green mark have been verified and approved by the community.
Most of the coins on the Waves platform aren't accompanied by a green mark, this doesn't imply that those tokens aren't tradable or that something is wrong with the coin. It only means that the Waves team has not yet verified or approved the Token. At this time, the process of verification is done by the Waves team. In the future this process will be handled by WCT holders. Please bear in mind when trading non-approved Tokens you double check the asset ID.
To get your asset verified, please use this sheet  and fill in all requested fields. Once the asset is accepted it gets added as a verified token to the GUI in the next GUI update. When this is done, you can see your token on the DEX with a green checkmark and it is easlily tradeable with all other tokens.
Below are some examples of verified Assets.