Dragon Ball is a manga series created by Akira Toriyama. It is the series that gave the birth of shounen genre, a great manga but after the Frieza Saga, it did not continue well due the publisher forcing Toriyama to continue and bring dead characters come back to life.
The verse is powerful, as they have serveral planetbusters after Saiyan Saga. They lack speed as no one in the verse can perform a FTL speed feat.
The manga itself is very popular, despite being very old (it has been translated into various languages through the entire world), giving it a very large fanbase. At the same time, it is very overestimated by its fan and underestimated by many Bleachwankers and Narutards,...
This gives birth to many a failed thread and hilarious situations, for example. Many of its fanboys have used it against many powerful universes like Bastard!, Tenchi Muyo!, Pokemon, DC and Marvel... during the early time of Mangafox's Arena, there are a lots of fanboys, trolls, and idiots claiming DBZ wins until Riverlia, Immortal Watching Dog, SiRCusS and many a great debater demolished their arguments and sent them running.
It also has many spin-off media with more than 4 anime series (Dragon Ball, Z, GT, Kai) and a new movie came out during 2009 (which it's a made of fail because the character has been completely alternated).
Dragon Ball GT isn't canon, despite the fact it is claimed to be canon by many fanboys. Toriyama has stated that it's an alternate universe and has no relation to the original storyline. In addition, there are 4 animated movies based on the original Dragonball anime, 13 based on the Dragonball Z anime, 1 movie based on DBGT, 4 TV specials based on the DBZ anime, an OVA which was originally part of a video game, a funny and thumbs down old Chinese live-action movie, and a made of fail Amerian live-action movie (the author sure has no understanding of DB) and Dragon Ball AF, you know it an April Fool's joke. This series is simply a fanfic and worthless.
It also seem there is a OVA written and directed by Akira Torimoya himself in 2008, it's took place 2 years after Part II of Dragon Ball, although the story is kinda random, it is still canon...regardless.
Standing on The Arena:
The universe has been widely acknowledge as a very powerful universe, however, there are still many people who try to make it sound stronger than it is, even resorting to using fan fiction (Okay, seriously, WTF?) to make the character win.
Top tier characters rest at massively hypersonic+ to sub relativistic(mach 31,000),destructive capacity and durability at Large Planet level+
The new movie Battle of Gods seems to feature FTL speeds for Whis and possibly Bills and SSJ God Goku and Star level DC and Durability.