When it comes to most spoken language in the world, English is only ranked #2

• Mandarin Chinese (1.1 billion speakers)
• English (983 million speakers)
• Hindustani (544 million speakers)
• Spanish (527 million speakers)
• Arabic (422 million speakers)
• Malay (281 million speakers)
• Russian (267 million speakers)
• Bengali (261 million speakers)
  _(source)

Most English speaking people think they will have no problem when traveling abroad thanks to English. Try China or Russia, and you will learn the hard way that it's not always so obvious ;)