Transitions show the relationship between or among segments of information in a piece of writing.

They help readers follow the logic of an argument or assertion, how the item preceding the transition relates to that which follows it.

Abrupt changes are most likely to need a transition: a shift from cause to effect, a contradiction, a contrast.

Transitional expressions:

To add or show sequence - again, also, and, and then, besides, equally important, finally, first, further, furthermore, in
        addition, in the first place, last, moreover, next, second, still, too

To compare - also, in the same way, likewise, similarly

To contrast - although, and yet, but, but at the same time, despite, even so, even though, for all that, however, in contrast, in
        spite of, nevertheless, notwithstanding, on the contrary, on the other hand, regardless, still, though, yet

To give examples or intensify - after all, an illustration of, even, for example, for instance, indeed, in fact, it is true, of course,
        specifically, that is, to illustrate, truly

To indicate place - above, adjacent to, below, elsewhere, farther on, here, near, nearby, on the other side, opposite to, there,
        to the east, to the left

To indicate time - after a while, afterward, as long as, as soon as, at last, at length, at that time, before, earlier, formerly,
        immediately, in the meantime, in the past, lately, later, meanwhile, now, presently, shortly, simultaneously, since, so far,
        soon, subsequently, then, thereafter, until, when

To repeat, summarize, or conclude - all in all, altogether, as has been said, in brief, in conclusion, in other words, in
        particular, in short, in simpler terms, in summary, on the whole, that is, therefore, to put it differently, to summarize

To show cause or effect - accordingly, as a result, because, consequently, for this purpose, hence, otherwise, since, then,
        therefore, thereupon, thus, to this end, with this object