Google operates in many industries, for example Google maps, Android and the most obvious search engine.
1) Google Search Engine's competitors- Yahoo and Bing.
Previously there was AskJeeves, Lycos, Altavista but they have either shut down or shrunk to a size where they have become insignificant.
2) Google maps' competitors- Yahoo maps, Bing maps, Streetmap, Apple maps
3) Google bought YouTube
YouTube's competitors- Vimeo, Dailymotion and Vidme
4) Google mail or Gmail- Yahoo mail, and Hotmail
5) Google Chrome- Firefox, Internet explorer and Safari
6) Google Android- Apple iOS, Microsoft windows, and Blackberry