Communication is, of course, important in marriage. But communication includes every message, every feeling, every desire, every thought that is conveyed to the other person. Some communication is helpful, some is destructive. The most useful knowledge is knowing how to avoid the unhappy, harmful interactions. Seeing how happy and unhappy couples communicate differently might help.

Our stereotype of a happy marriage is a couple who like each other, understand each other well and settle disputes easily. Yet, some stable marriages do not fit this stereotype. Some are volatile ie fighting openly but making up passionately and others carefully avoid conflicts, i.e. they don't "work things out" but agree to disagree. Apparently happy couples have developed various ways of handling the inevitable conflicts, unhappy couples haven't. Unhappy couples first criticise the partner's behaviour but that gradually evolves into attacking his/her personality which eventually degenerates into expressing abusive contempt. Naturally the attacked partner becomes defensive, perhaps by saying "it's not my fault," by feeling indignant and counter-attacking, or by completely withdrawing emotionally (stonewalling). Both the attacks and the defensive refusal to deal with the issues are big parts of the problem. Men in unhappy marriages, especially, do not listen to the verbal messages nor pick up on their wives' non-verbal messages. Unhappy couples frequently just exchange hostile accusations - "You don't care about me--only about yourself" whereas happy couples may argue, even shout, but would then explore the topic more - "Are you really as unconcerned with this problem as you look?" ending up resolving the difficulty. Here is a summary:

Poor communicators Good communicators
A steady flow of criticism & putdowns or blaming Accentuate the positive and the hopes for the future
Neither partner feels cared for and listened to, they are too busy defending themselves Both partners try to stay calm, see the other's point and show respect, look for a compromise
Get off the topic, find no solutions and throwing all kinds of complaints & insults at the partner Stay on topic, be specific about the problem rather than expressing contempt, find a solution both can accept
"Psychoanalyse" the partner, name-call, show contempt by mocking, rolling eyes, insulting them, lots of Yes-buts and counter-attack, do a lot of interrupting Listen carefully, give empathy and positive responses, assume responsibility for your own feelings - "I" statements, overlook the insults and focus on the complaint. State tentative opinions, not absolute certainties
Show a determination not to "give in," anger and eventually, deadly silence Understand and forgive each other, both give in about 75% of the time
Respond to criticism with defensiveness, such as denying everything, making excuses, stating he/she is emotional Respond to criticism as useful information rather than as an insult, a little empathy will work miracles.
Just not responding, tuning them out when you are fed up with the attacks, stonewalling Realise that stonewalling is an insult, it says you are contemptible and not worth listening to. You must listen for the pain and hear the unspoken plea to improve the relationship