It's well known that the Japanese are an extremely polite people, and this politeness is actually infused into their language. The first kind of polite language students of Japanese encounter are "formal verbs," which all end in -masu, e.g. tabemasu (to eat, formal) instead of taberu (the informal version of the same verb). In 90% of situations, foreigners can get by speaking with the formal verbs, which is nice because these verbs are very easy to learn and internalize. In more formal situations (business settings, weddings etc.) there are higher levels of polite speech called keigo which can be challenging even for Japanese people to master. The basic idea of politeness is to "exhalt" the person you're addressing (and his company or organization) to a higher level while humbly lowering yourself (and your company/organization) at the same time. A good example is the word for "person" which is usually hito in most situations, but if you're referring speaking polite Japanese, you'd use kata when referring to a person you're trying to be polite to (say, the representative of a company you want to do business with) while using the term mono as a "humble" term for the wretched, worthless employees in your own company. There's no better way to learn a grammatical lesson than by getting it gloriously wrong, and I've gotten kata and mono switched around when trying to secure a business relationship with a new company, no doubt with humorous results for people on the other end of the phone (though I was able to get the contract).