A campaign is the top-level structure in Facebook Ads Manager, where you define your advertising objective, such as awareness, consideration, or conversion.
Ad sets allow you to set targeting, budget, schedule, and placements for your ads. Multiple ad sets can exist under one campaign.
Audiences are groups of people targeted based on demographics, interests, behavior, or custom data (like website visitors and customer lists).
Reach refers to the total number of unique people who see your ad. It’s a measure of how many individuals were exposed to your campaign.
CTR is the percentage of people who clicked on your ad after seeing it. A higher CTR indicates effective ad creative and targeting.
ROAS measures the revenue generated from an ad campaign relative to the amount spent. It’s a key metric for evaluating campaign profitability.