"Every Mission requires objectives to be accomplished in order to succed; usually such objectives are divided into two categories: this is the second one. Secondary Objectives comes in two kinds: those that are considered optional for their triviality and those considered so difficult to attain that their fullfillement is a hope at best. In the first case, you have the possibility of attaining success in a side-quest which would bring agevolation the the Squad at some degree, although it is not so essential, in the latter case, instead, you must try to reach an important goal that is however considered to be out of your reach unless you perform really well. The Secondary Objectives fullfillement always brings a Reward upon you in the form of Credits, so, trying your best is the fastest route to stocking up lots of credits. Remeber, however, that, as the name implies, such objectives are Secondary, this means that there are some others that are Primary and, as such, you should try not to jeopardize your true goals only for your lust for credits"