Some 40% of adults have experienced online harassment, according to a study from the US Pew Research Internet Project.
From name-calling to other threats, harassment is a common part of online life for many, its research suggests.
While men are more likely to experience name-calling, women are more vulnerable to sexual harassment and stalking.
The report comes amid a rise in social media abuse aimed at women in the games industry.
The report found that 73% of American adult internet users had witnessed online harassment - from being called offensive names to witnessing someone being stalked online.
It found that young adults - aged 18-29 - are most likely to experience online harassment, with 65% of internet users in this age group claiming to have fallen victim.
The vast majority of harassment took place on social networking sites, according to the research.
The report looked at six types of abuse:
- Offensive name-calling
- Attempts to purposefully embarrass
- Harassment for a sustained period of time
- Online threats to physically harm
- Online stalking
- Sexual harassment
"It was striking to see how different varieties of harassment impacted different groups on different platforms, and the range of reactions online harassment elicited," said report author Maeve Duggan.
Of those who had personally been harassed online, the majority chose to ignore it, she found.
Young women are particularly vulnerable to sexual harassment and stalking online, she told the BBC.
Her research also found that gaming platforms were seen as the least welcoming to women, with 44% of people saying such forums were more geared towards men.
Last month, more than 2,000 people signed an open letter calling for an end to "hateful, harassing speech" on Twitter and other social media, following death threats to feminist games reviewer Anita Sarkeesian.
Her series on the portrayal of women in video games led to what she described as "some very scary threats" which forced her to leave her home.