Conceptually, it's
Celtic. Bards were composers and reciters of epic poetry which was the common form of entertainment. These peoples memories were fantastic. I've heard they could hear a thousand words a single time and be able to recite them back flawlessly. In a world without writing, memory develops much better, and the bards were the best of the best. Poetry was used to remember such tales simply because it's easier to remember a rhyme or pattern than it is to remember unstructured prose.
There's quite a bit of crossover between a bard and a
druid, historically speaking, since they both were Celtic professions involved with poetry -- again, no writing among commoners, so knowledge is often memorized as poetry. Druids were simply focused more on administration, religion, and medicine, and bards were focused more on the poetry. Bards were heralds of knowledge; remember, poetry = song = knowledge.
Bards held some religious status, since some of their compositions were eulogies. Again, this is similar to druids. You hear Scottish tales of "warrior-poets" in movies like Braveheart. They're talking about warrior-
bards. The norse concept of a
skald -- the historic concept, not the Bard/Barbarian multiclass people always make -- is basically equivalent to a historic bard. The equivalence of magic an music is something I think we appreciate even today. We still speak of being enchanted and charmed by a tale or moving ballad. These people dedicated their lives to their trade in a time when art for art's sake was not at all common.
Mechanically, the original
Bard was published in The Strategic Review (the original name for Dragon magazine) and when the AD&D 1e PHB was printed, it was published as specialty class in the Appendix of the PHB along with the psionics stuff and the planar cosmology. Honestly, it belongs more in 1e Unearthed Arcana. It's famed as the class that's the most difficult to qualify for, and also as the class that's potentially the most powerful and has potentially the most hit points.
To quote the wiki entry for 1e AD&D Bards:
To become a bard, a human or half-elf had to begin with very high ability scores: Strength 15+, Wisdom 15+, Dexterity 15+ and Charisma 15+, Intelligence 12+ and Constitution 10+. These daunting requirements made bards one of the rarest character classes. Bards began the game as fighters, and after achieving 5th level (but before reaching 8th level), they had to dual-class as a thief, and after reaching 5th level as a thief (but before reaching 9th level), they had to dual-class again to druid. Once becoming a druid, the character then progressed as a bard, but under druidic tutelage.
Note that this appears to allow half-elves to dual class, while normally they're required to multiclass. Also note that this class allows you to run around with 7d10 + 8d6 + 10d6 hit points. You'd easily have 22 hit dice before the party Fighter hit name level (at 250,000 for level 9 with all of 9d10 hit points). With no con mod, that's an
average of 100 hp. Remember:
Lolth had 66 hp. You can also go all the way to level 23 on the Bard table, or 38 levels of progression overall, which I think makes Bard officially the longest class ever printed, even counting the 36 levels of BECMI classes (although Bards are only actually level 23 since they're dual classed, IIRC). Note also that since you begin play as a Fighter, you can begin play with percentile strength.
