Different countries may also have different laws around privacy that could hamper Twitter's ability to offer certain ad products or analytical tools in those countries, the company said. In particular, foreign data protection, privacy, consumer protection, content regulation and other laws and regulations are often more restrictive than those in the U.S., Twitter said.
The European Union, for instance, has traditionally taken a broader view of what types of data are subject to privacy and data protection, Twitter said, and some proposals that are pending before various regulatory bodies "could significantly affect our business," the company said.
There is one regulation tied to the 1995 European Union Data Protection Directive being considered that may include stricter operational requirements for companies that process personal information, Twitter said. Twitter does not collect extensive personal information from its users such as their age, Twitter said in its filing, but that may change with the introduction of new laws, or just new thinking on Twitter's part.
Google has already run into some trouble in terms of how its user data policies are interpreted by regulatory authorities in France.
There are differences in the competitive landscape too that could be problematic for Twitter. The company's obvious competitors include Facebook (which got nine mentions in the filing), Google, LinkedIn, Microsoft and Yahoo, but there are smaller ones overseas.
In South Korea, for instance, Twitter said it faces intense competition from Kakao's messaging service, which offers some of the same communications features as Twitter does.
These types of established international competitors, Twitter said, may impede its ability to increase its number of users and ad sales in those markets.
Advertisers might also have different demands in different markets, Twitter said, such as during times of political upheaval, or may not be familiar with all of Twitter's various ad products.
In its IPO filing, Twitter reported total annual sales in 2012 of US$317 million. Eighty-five percent of that came from advertising.