SAN FRANCISCO — When Google took a video camera to Times Square in 2009 and asked passers-by what a browser was, most of the answers were hilariously incorrect, from ‘‘a search engine’’ to ‘‘broadband’’ to ‘‘Yahoo.’’

But even if consumers are not so sure what Web browsers are (programs such as Internet Explorer and Firefox), they have become a crucial business for tech companies like Google and Microsoft. They are now the entry point not just to the Web but to everything stored online, such as Web apps, documents, and photos.