Meitantei Conan (名探偵コナン), officially translated as Detective Conan, is a Japanese manga series written and illustrated by Gosho Aoyama. I have been reading and watching it for more than 10 years - well, to be precise, exactly 12 years and 10 months. Personally, I like this animation because it is about trying to figure out solution to the mysteries. Kindly read through the following details and you will understand why do people like this series so much.

Detective Conan is about an elementary school boy named Conan Edogawa. He solves mysteries and crimes through reasoning and logic and with the help of friends and nifty gadgets. Conan is really a 17-year-old famous high school detective, Shinichi Kudo. While investigating some suspicious activity, Shinichi was knocked over the head by a man dressed in black. During his semi-conscious state, an experimental drug was forced down his throat that was meant to kill him. Instead, Shinichi was shrunk into a little kid. In order to prevent the men who did this to him from hurting his friends and family, Shinichi changed his name to Conan Edogawa and now lives with his girlfriend, Ran and her dad.

Shinichi Kudo (工藤 新一
A well known High School Detective who helped solve cases which the police could not. One day, he investigates a suspicious man. Later he is attacked and forced to swallow a poison called APTX4869 which turns him back into a child. He takes on the alias Conan Edogawa to keep his real identity secret from everyone (besides a select few) to protect his loved ones, particularly Ran. 

Conan Edogawa (江戸川 コナン)
He is the alias used by Shinichi Kudo in his shrunken form. Indeed, he took the appearance of a 7 year old boy after being forced to swallow a poison. Besides his changed appearance, the poison did not inflict any other damage and therefore he still has the brain and mind of an adult.

Ran Mouri (毛利蘭)
Ran is a childhood friend of Shinichi Kudo. She is the daughter of Kogoro Mouri, a private detective. Ran is the captain of the karate team of Teitan High School and therefore is very powerful as demonstrated when she won her Regional Championship. However, she gets easily frightened by the idea of ghosts or monsters.

Kogoro Mouri (毛利 小五郎)
Kogoro is a private investigator, but he prefers to laze around all day. Because of his behavior around attractive woman, he often embarrasses his daughter Ran Mouri, and while it is not the reason why his wife left him, it is the reason why she hasn't come back.