The Matchlock was a welcome improvement in the mid-fifteenth century and remained in use even into the early 1700s, when it was much cheaper to mass produce than the better classes of firearms with more sophisticated ignition systems. The Matchlock secured a lighted wick in a moveable arm which, when the trigger was depressed, was brought down against the flash pan to ignite the powder.
This allowed the musketeer to keep both hands on the gun, improving his aim drastically. The gun had its weaknesses, though. It took time to ignite the end of the wick, which left the musketeer useless in case of a surprise attack. Also, it was difficult to keep the wick burning in damp weather. For the most part, longbowmen were more effective in battle than the musketeers.
The one real advantage the musketeers possessed was the intimidation factor which their weapons provided. The first important use of musketeers was in 1530 when Francis I organized units of arquebusiers or matchlock musketeers in the French army.