Blue the dog and her friend Steven Burns

To solve the clues, Steve relies on such household items as Mr. Salt and Mrs. Pepper Shaker to help figure out the mystery of the day.

Besides her human hosts Steve & Joe, Blue's other friends included her dog friends, Magenta, a Blue's best girl friend; Sprinkles, Blue's baby multi-colored brother (who debuted on the 2006 10th anniversary special) ; Green puppy, a girl; Orange Kitten, a girl; Purple Kangaroo, a male; Polka Dots, a green dog with purple polka dots; Periwinkle, a talking blue male cat, and Turquoise, Blue's pet turtle.

Blue's inanimate object friends included

• Side Table Drawer, a piece of talking furniture where Blue stores her clues notebook
• Slippery Soap, a talking bar of soap
• Tickety Tock, a talking clock
• Mr. Salt and Mrs. Pepper, a pair of French speaking shakers and their children, Paprika, a girl; Cinnamon, a boy; and baby  Oregano.
• Shovel and Pail, talking sandbox toys
• Mailbox, that delivers Blue's mail
• The Felt Friends, Freddy and Fifi who live in a world of colored felt shapes

Other characters on the show included Miss Marigold, Blue's Teacher; Moona, a crescent shaped moon fairy with pigtails who tells the time; Horace, Steve's stuffed anteater; and Boris, Joe's toy duck.

In 1998, Blue celebrated her birthday on "Puppy's Puzzle Party" that featured such guest as Rosie O'Donnell, twins Tia and Tamara Mowry and singer Gloria Esteban. In 2000, a Blue's Clues movie called Blue's Big Musical debuted.

Beginning in 2002, Donovan Patton as Joe replaced Steven Burns as the host of the show.

Closing Theme Song

Now it's time for so long.
But we'll sing just one more song,
Thanks for doin' your part, you sure are smart,
You know with me and you,
and my dog (our friend) Blue,
We can do anything that we wanna do!