This may or may not be a big assumption to make in answering this question, but one might assume you are speaking from an American point of view:
In most countries, including USA, the most popular sports are team games.
There are some Asian countries, who culturally value individual excellence, where certain individual sports are perhaps the most popular. In some Asian countries, for instance, Table Tennis and Badminton are the most popular sports ... but even within these, the popularity of tennis continues to grow.
Tennis is probably growing in popularity with time in many countries because now that it is fully professional, people see it as a means of making a living - and, possibly, a good one.
To return to the original question proper: Among the "individual sports" available, tennis is probably the most popular sport in most countries in the world ... but most countries still prefer one or another team sport to tennis.
USA would have a number of team sports more popular than tennis - especially, in winter.
Tennis is somewhat popular though not even close to as popular as hockey.
Yes, tennis is the 4th most popular sport in the world, 13th most popular sport in America, and the most popular individual sport in the world.
in england and in the u.s.a
The most popular tennis magazine in the world is "Tennis" magazine. "Tennis" is a monthly magazine that has been published for over forty years and features news from the world of tennis.
Although tennis is popular allover Indonesia. Bali, a province in Indonesia is known for the longest running and most popular charity tennis event. There are many tennis courts and clubs in Bali.
Soccer is the most popular sport in Paraguay. However tennis, Golf, and biking are also very popular there
Tennis is popular.
Tennis is the most popular individual sport.
this is open for discussion, but tennis is very popular.
table tennis or dodgeball