What is a boosted post?
A boosted post is a post to you pages news feed that you can apply money to in order to boost it to an audience of your choosing. This is the simplest way to advertise on Facebook. Boosted posts differ from Facebook ads because they are not created in Ads Manager and don't have all of the same customisation features.
When you choose an organic post to boost you are able to do the following:
Choose who you want to reach: you'll pick a target audience of the type of people you want to connect with.
Say how much you're willing to spend: you'll state how much you want to spend over the course of your entire campaign.
Choose how long you want to run your ad: once you click Boost and your ad is approved, people in your target audience will see your ad in their News Feed for the duration you've set.
If you don't want to boost a post from your organic news feed and don't want your ad to be seen organically - you can master a new post and instead of clicking Publish, click Boost.
What more can I do with Facebook ads?
Facebook ads are created through Ads Manager and offer more advanced customisation solutions for example:
Choose from a variety of ad objectives: Choosing an ad objective early on will help you to focus on which campaign type best aligns with your current business goals. Where boost allows you to choose such objectives as engagement and reach, the full ads system in Ads Manager lets you choose objectives like conversions, and lead generation and video views.
Use advanced targeting capabilities: Boosting posts let you decide on interests, age and gender for your ad targeting. Using Ads Manager, you can use more advanced tools to create custom audiences of those that have engaged with your pages & your website as well as lookalike audiences and more.
Choose different ad placements: When you boost a post, you'll be able to check or uncheck whether or not you want to place your ad in Instagram in addition to Facebook mobile and desktop News Feed. Within Ads Manager, you get the added benefit of choosing placements in Facebook News Feed side ads, Messenger ads, Instagram stories, instant articles, and Audience Network.
Give yourself more creative control: With Facebook Ads created through Ads Manager, you get access to a number of different creative formats including carousels, slide shows, instant experience formats to name just a few.
For more about Facebook advertising see:
What are 'audiences' for Facebook advertising?
How to choose the right objective for Facebook advertising.