Interactive Illustration $1$: Platform Network Effects in the Core Reading uses Facebook to illustrate different types of network effects. According to this illustration, $(1)$ an increasing number of users makes Facebook more attractive to potential new users, which $(2)$ makes Facebook more attractive to advertisers. $(3)$ As Facebook becomes more attractive to advertisers, however, advertisers compete for a limited number of keywords, driving up advertising prices and potentially discouraging some businesses from advertising on Facebook. Examples $1,2,$ and $3$ illustrate, respectively: