Table:
|  | Year Ended December 31, |  |  | 2019 to 2018 |  | 2018 to 2017 |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  | 2019 | 2018 | 2017 | $ change | % change | $ change | % change |
| Domains | $ 1,351.6 | $ 1,220.3 | $ 1,057.2 | $ 131.3 | 11 % | $ 163.1 | 15 % |
| Hosting and presence | 1,126.5 | 1,017.6 | 847.9 | 108.9 | 11 % | 169.7 | 20 % |
| Business applications | 510.0 | 422.2 | 326.8 | 87.8 | 21 % | 95.4 | 29 % |
| Total revenue | $ 2,988.1 | $ 2,660.1 | $ 2,231.9 | $ 328.0 | 12 % | $ 428.2 | 19 % |
Paragraphs:
Comparison of 2019 and 2018
Revenue
We generate substantially all of our revenue from sales of subscriptions, including domain registrations and renewals, hosting and presence products and business applications. Our subscription terms average one year, but can range from monthly terms to multi-annual terms of up to ten years depending on the product. We generally collect the full amount of subscription fees at the time of sale, while revenue is recognized over the period in which the performance obligations are satisfied, which is generally over the contract term. Revenue is presented net of refunds, and we maintain a reserve to provide for refunds granted to customers
Domains revenue primarily consists of revenue from the sale of domain registration subscriptions, domain add-ons and aftermarket domain sales. Domain registrations provide a customer with the exclusive use of a domain during the applicable contract term. After the contract term expires, unless renewed, the customer can no longer access the domain.
Hosting and presence revenue primarily consists of revenue from the sale of subscriptions for our website hosting products, website building products, website security products and online visibility products.
Business applications revenue primarily consists of revenue from the sale of subscriptions for third-party productivity applications, email accounts, email marketing tools and telephony solutions.
The following table presents our revenue for the periods indicated:
The 12.3% increase in total revenue was driven by growth in total customers and ARPU as well as having a full year of revenue from MSH in 2019, partially offset by the impact of movements in foreign currency exchange rates. The increase in customers impacted each of our revenue lines, as the additional customers purchased subscriptions across our product portfolio.
Domains. The 10.8% increase in domains revenue was primarily driven by the increase in domains under management from 77.6 million as of December 31, 2018 to 79.6 million as of December 31, 2019, increased aftermarket domain sales and international growth
Hosting and presence. The 10.7% increase in hosting and presence revenue was primarily driven by increased revenue from our website building and website security products as well as our acquisition of MSH.
Business applications. The 20.8% increase in business applications was primarily driven by increased customer adoption of our email, productivity and telephony solutions.
Question:
How many types of revenues are there?
Answer: Objects satisfying the requirements:
Domains 
 Hosting and presence 
 Business applications
As a result, the answer is 3