Millions of young people are writing blogs . Millions of others are reading them. The word "blog" is a short way of saying Web log. Many popular Web sites now offer free, easy ways to create personal Web pages and fill them with writings and pictures. Web sites called "Face book" and "My Space" are some of the most popular blog sites for young people.  Blogs offer young people a place to show their writings and feelings. They can also be helpful to connect young people with others. But blogs can become dangerous when they are read on the Internet by millions of people all over the world. Recent studies show that young people often tell their names, age and where they live on the Internet. That may not be safe for them. This personal information puts them in danger when found out by dangerous people who want to hurt them. Students can also get into trouble when they put information about others on their blogs.     As a result, many schools don't allow using blogging web sites on school computers. Many schools have also begun teaching parents about the web sites. Parents should know what their children are doing online and should read their blogs to make sure they are not giving out personal information. One way to keep away from these problems is to use programs  so that blogs can be read by "friends only." people can read the website only if they know a secret word chosen by the blogger. This passage is mainly about   _  .
the safety of children's blogs how to surf the internet students' action at school communicating with parents at home