Pixels

Pixels are the main currency in Starbound. It can be used to buy items from merchants, and you get it from selling items.

Normally you would get 20% of the item's pixel value when you sell an item, or 30% when selling via Terramart Shipments. However, different shops and merchants (especially shops on spacestations or vending machines) may have altered buy/sell prices. Most liquids, most blocks (like Dirt) and some items will cost 0 pixels (so selling them won't give you anything).

It's not possible to carry more than 10 millions pixels (anything beyond that will be lost), but you can craft items like 10k Voxel to store them.