Everquest's bard is one of the most unique classes to ever enter an MMO. It sounds silly - a guy who plays music all the time. In game, they are primarily focused on keeping their party buffed to the hilt with a variety of powerful magic songs, "twisting" the buffs together by rapidly switching between them. Hymn of Restoration and Cassindra's Chant of Clarity, for example, greatly increase both health and mana regeneration for the party, helping every class do their job more effectively and keeping downtime to a minimum. Their spell Selo's Accelerando increases the speed of the party, making them indispensible for when travelling over long distances, as the highest level versions are even faster than the druid spell Spirit of the Wolf.
Bards wear plate; seriously increasing their survivability. Their abilities are also mostly low-threat, so bards should be getting hit only in a few situations. Many bard spells are made more effective if you're using an instrument, but not all of them do. Instrument modifiers are also present on certain pieces of armor and weapons, so it's not always necessary to tote around an instrument. The bard is an excellent class for players who like to play in parties and enjoy buffing, but don't like the boring process of going through each party member to cast a spell on them. The group-wide buffs that the bard provides need to be constantly refreshed, making this a class that you need to give your full attention to in order to excel at.
Their primary stat is intelligence. The class is highly complex, and difficult to access for newcomers unless they slowly build up their knowledge as they level up. Bards can solo passably, but the amount of utility that they bring to a group puts them in high demand. You'll be able to survive easily, but the amount of damage that bards do leaves a lot to be desired. You can easily switch up your spell choices depending on your party composition. Have a lot of melee? Use a haste song combined with a mana regeneration one to keep your healers topped off. Almost full with casters? Buff their spell damage and mana regeneration.
Proper use of Selo's Accelerando also makes bards fantastic kiting partners, making them a great class for duoing monsters that are much higher level than you. In raids, they're either used to power up the tank, pull monsters or provide support and protection to casters.