One of these is that people now move around more often for work, distancing themselves from friends and family members who could play matchmakers.
Some, such as JDate, which is designed for Jewish lonely hearts, and Ave Maria Singles, which focuses on Catholics, serve specific religious or ethnic niches.
Others appeal to rather less conventional interests.
Yet while looking for love online is no longer seen as an act of desperation, the digital-dating industry still generates plenty of controversy.
Its critics charge that sites' claims of matchmaking prowess are often greatly overblown.
The spread of fast broadband connectivity in many countries has also encouraged people to dabble in online dating.