1) 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.

2) The first successful mass-produced personal computer, the IBM PC, was introduced in 1981 and played a significant role in popularizing the use of computers in homes and offices.

3) The invention of the transistor by Bell Laboratories in 1947 revolutionized electronics and paved the way for the development of smaller, more efficient electronic devices.

4) The Atlantic Ocean is the second-largest ocean and is known for its strong ocean currents, including the Gulf Stream.