What is the difference between using a daily budget versus a lifetime budget for an ad campaign?

The difference between a daily budget and a lifetime budget lies in how the ad spend is distributed over the campaign's duration. A daily budget sets an average amount that the campaign will spend each day, allowing for flexibility based on performance. A lifetime budget sets a total amount the campaign will spend over its entire run, and Facebook's algorithm automatically distributes the spend across the campaign's duration, potentially spending more on some days and less on others to maximize results within the budget. For example, if a campaign has a daily budget of $20, it will generally spend around $20 each day. If a campaign has a lifetime budget of $140 and runs for 7 days, Facebook may spend more than $20 on days where performance is strong and less on days where performance is weaker, but the total spend over the 7 days will not exceed $140. Daily budgets provide more control over daily spending, while lifetime budgets allow Facebook to optimize spending across the entire campaign duration.