These security issues come in all sizes. Everything from ensuring that documents transmitted across the Internet arrive where they are supposed to and protecting against viruses hidden in downloaded software, to defending corporate computer systems from attack by hackers and securing data critical to national security, falls under the broad heading of "Internet security."
安全問題可大可小，從個人在網路上傳送文件可能被攔截、下載來路不明的軟體導致電腦中毒、企業內部電腦主機被駭客入侵，到國防資訊情報戰，都屬於安全範圍。