If you're a student of the Japanese Language you will probably already have learned to use verbs to describe  actions. For instance, you could say kaze o hikimashita "I caught a cold" or watashi wa tabemasu "I will eat". By using -masu verbs you can describe the future, past, and habitual present tenses (something like "I walk to work everyday").

But what if you wanted to say "I am eating (right now)" or "She was wearing a red hat (at the time)"? Both these sentences are progressive. Actually, it's really quite simple. You simply use the -te form of a verb and the verb imasu (meaning "to exist"). So for example, to say "I am easting" we take the verb tabemasu ("to eat") and we use its -te form, tabete (-masu is replaced by -te). You can think of the -te like the "-ing" in English verbs. Next, you simply add the correct form of imasu. Since I am eating is both present and positive, imasu is the correct conjugation. So, tabete imasu means "I am eating".

To say "I was eating", we need to change the tense of the verb. You can't change verbs in their -te form, ever. Likewise, in English when you change "I am eating" to "I was eating" the "eating never changes, simply the existance verb, "am" into "was". Japanese is exactly the same, to say "I was eating" we simply change imasu to its past tense form, imashita so we finish with tabete imashita "I was eating".

Of course, once you've understood this, it will be simple to create both negatives and past-negatives. We simply use the correct form of imasu again. "I am not eating" uses the present negative form of imasu, which is imasen. So it's tabete imasen "I am not eating".
 
Finally, "I was not eating" uses the past negative, imasen deshita. So, it's tabete imasen deshita "I was not eating".

This area of Japanese is quite simple, and made a lot easier thanks to the logical rules that the vast majority of the language uses. All polite verbs just have those four form masu, mashita, masen, and masen deshita. With the addition of "mashou" for some future tense situations. Unlike English, which does have some guideline rules, but also has 1000's of exceptions to those rules. One can only feel for a fellow student of English. Progressive tenses are easy for English speakers because the Japanese is so alike. tabete imasu literally does mean "I am eating".

They are called progressive simply because the action (verb) has not yet been completed, it's still happening, either "right now" or "at the time" in the context of talking about the past. For instance, "She was drinking Coffee" kanojo wa kouhii o nonde imashita is progressive. At the time, the action of drinking wasn't finished, it was progressive.

Let's look at some example sentences. English translations are provided.

aoi  jiinsu o haite imasu
I am wearing blue jeans.

hiromi-san wa kireina doresu o kite imashita ne?
Hiromi was wearing a pretty dress, don't you think?

doko de hataraite imasu ka?
At where are you working? = Where do you work? (in normal English)

ibeeyu de hataraite imasu. Shachou de, Kyuuryou ga totemo ii.
I work at Ebay. I'm the company presedent, the pay is very good.

itte imasu!!
I'm going!!

nihongo o shitte imasu
I know Japanese

eigo o shitte imasu ka?
Do you know English?

nihongo o shirimasen
I don't know Japanese

That concludes this guide. I will be writing more guides on other areas and things, but you can contact me at yggdrassill@hotmail.co.uk with any questions.