CFDs are a leverage product and can involve a significant risk of loss. Trading CFDs may not be suitable for all, therefore you should ensure that you understand the risks involved and take into account your individual circumstances.
Trader's Glossary

What is Spread?

Bid and ask prices are determined by the most a buyer is willing to pay for a unit of a given asset, and the least that a seller is willing to accept in order to sell it. The spread is the difference between these two figures.