A brief, brief summary of Power Rangers

From left to right: 
Zack, the Black Ranger. 
Kimberly, the Pink Ranger. 
Jason, the Red Ranger. 
Trini, the Yellow Ranger. 
Billy, the Blue Ranger. 

These five "teenagers with attitude" were chosen to defend the world from the menace of Rita Repulsa.

 
Rita decided to fight fire with fire, and created her own evil ranger.  Placed under an evil spell, Tommy proved to be a dangerous adversary to the Rangers, but the spell was soon broken, and Tommy joined the forces of good.  Angered, Rita drained Tommy of his powers.  The Rangers were five once more.  One day though, the Rangers found themselves without their power coins, and Tommy reassumed the green powers, beginning a period where his power would rapidly fluctuate.
 
Times, they were a changin'.  A new villain by the name of Lord Zedd graced the scene.  The green powers finally drained to nothing, and so not to be vulnerable to this new foe, Zordon and Alpha created the White Ranger.  With these new powers, Tommy assumed the role of leader.  The timing was most appropriate, for not long after, Jason, Zack and Trini left the team to assume the role of  Teen Peace Ambassadors.  Their ranger suits were to be filled by Rocky, Adam and Aisha respectively. 
 
When the Thunder Zords and the White Tiger Zord were destroyed, the rangers were in need of new powers.  Their search led them to Ninjor,  who forged the original power coins, and upon gaining his trust, the teens were empowered with their animal ninja spirits.  Kimberly was to learn the vulnerabilities of these new powers when her coin was stolen, and her powers drained.  The thief, an Australian by the name of Kat, was under a spell of Rita's.  When Kat's inner kindness enabled her to break free, she became the ideal candidate to replace Kimberly, who left Angel Grove to represent the USA in the Pan Global games.
 
Rita and Zedd, led by Rita's father Master Vile,  eventually managed to destroy the Command Center, and the Power Coins.  The rangers searched individually for fragments of the powerful Zeo Crystal.  Tanya would replace Aisha, and  similarly, Billy decided to retire from active duty.  While battling the Machine Empire,  the team would return to six members with the arrival of Trey, the Gold Ranger.  A refugee from another planet, Trey handed the power to Jason, who had returned from the Peace Conference.  Jason would only hold these powers for a short time.
 
The arrival of Divatox, an intergalactic pirate, meant the Zeo powers provided inadequate protection for the Rangers.  Turbo Power was the key to defeat this new menace, though Rocky was unable to assume the responsibility, and was replace by Justin, a 12 year old genius.  The teens would have a new mentor, Dimitria, who was assisted by Alpha 6.  As four of the rangers were now graduated from high school, Dimitria saw it was time for some fresh blood, and Ashley, Carlos, Cassie and T.J. were to become the newest generation of Power Rangers.  When it became time for the "Chase into Space" to save Zordon, Justin stayed behind on Earth, his Dad too important to abandon.
 
Power Rangers in Space....