All dissimilar materials have the potential to react with each other when they are brought together in the presence of a catalyst. In most circumstances this reaction is so mild as to be of no importance, but when the wrong materials are used in combination and then exposed to an electrolyte such as water the effects can become much more noticeable. For applications where humidity is low then you can generally ignore galvanic corrosion. If on the other hand you are working on a project for use in damp conditions or outside then it is best to pay some regard to the possible effects of galvanic corrosion. As a rule it is best to use metals which are as close together as possible in the table below. Doing this will help to eliminate any possibility of galvanic corrosion.
If you do have to mix materials then take a look at the galvanic compatibility section

Below is a link to our downloadable Galvanic Reaction Chart