1) The word "guitar" contains three vowels: U, A, and I.

2) The world's largest particle accelerator, the Large Hadron Collider, is located near Geneva, Switzerland, and spans a circumference of 17 miles (27 kilometers).

3) Emma Watson is a British actress and activist known for her role as Hermione Granger in the "Harry Potter" film series. She has since starred in films such as "The Perks of Being a Wallflower" and has been actively involved in promoting gender equality and women's rights.

4) The first graphical web browser, Mosaic, was released in 1993 and played a key role in popularizing the World Wide Web.