Twitter Ads are priced using an auction model. Auction-based pricing helps ensure advertisers achieve optimal results while creating the best possible experience for users. Advertisers have three options to choose from when determining how to set bids for their campaigns, "automatic," "maximum" or "target" bidding. It's important to note that these pricing options are available depending on which campaign-objective is selected. Twitter advertising works by means of an auction system. As explained below. When this is too tricky for you we can arrange this for you. "Automatic bidding" enables Twitter to auto-optimize bids for a given campaign objective and budget on the advertiser’s behalf. When selecting the automatic bid option, Twitter will attempt to enter the advertiser in auctions with the lowest bid possible, while also delivering on the advertiser’s overall campaign objectives. "Maximum bidding" allows advertisers to manually select how much a click or engagement is worth to their business.  "Target bidding" provides advertisers the ability to average out a specific price per engagement. When you select the Target bid pricing option, our system will optimize your bids to achieve this average cost target This bidding choice gives you the flexibility to win competitive auctions.