Of course, what was not mentioned is the flux type used for electric/electronics work...
Use only a rosin-core solder for any of your work in this field. Solid solder will require the use of an additional flux, which is jut too inconvenient for general purpose work. Whatever you use, make sure that it does not involve the use of an acid flux!
The finer the working area, the finer the solder should be. Oh -- and the same holds true for the solder iron tip and wattage. Large area = large tip and higher wattage; small area = smaller tip and lower wattage.
Be advised however that it is possible to cut back to far... For example, if you are using a tip and wattage that are extremely small, you may end up applying the iron to the joint for a longer period of time than might be desirable, whereas a somewhat higher wattage applied via the same tip size would heat the joint more rapidly, resulting in the heat being applied for a shorter period of time.