5.3.2. Social Networking Services# 2003 saw the launch of several popular social networking services: Friendster, Myspace, and LinkedIn. These were websites where the primary purpose was to build personal profiles and create a network of connections with other people, and communicate with them. Facebook was launched in 2004 and soon put most of its competitors out of business, while YouTube, launched in 2005 became a different sort of social networking site built around video.

In Web 2.0 websites (and web applications), the communication platforms and personal profiles merged. Many websites now let you create a profile, form connections, and participate in discussions with other members of the site. Platforms for hosting content without having to create your own website (like Blogs) emerged. And all of these websites became much more interactive, with updates appearing on users’ screens without the user having to request them.

Computers typically store text by dividing the text into characters (the individual letters, spaces, numerals, punctuation marks, emojis, and other symbols). These characters are then stored in order and called strings (that is a bunch of characters strung together, like in Fig. 4.6 below).

When computers store numbers, there are limits to how much space is can be used to save each number. This limits how big (or small) the numbers can be, and causes rounding with floating-point numbers. Additionally, programming languages might include other ways of storing numbers, such as fractions, complex numbers, or limited number sets (like only positive integers).