It's probably quite useful to have a look at the English tenses before we start with the Spanish one. So we have a chance to know what we are actually comparing.

The tenses give in general the time when something has happened, or more precise the relation between the point of time when somebody describes an action that happened. This action has different aspects that have influence on the tenses that are used.

Basically languages have present tenses, past tenses and future tenses.

English language describes the aspect of duration and whether things are done at the same time with the "continuous" forms.

simple present present continuous   I write you sleep he runs we think you arrive they read   I am writing you are sleeping he is running we are thinking you are arriving they are reading

future I future I continuous   I will write you will sleep he will run we will think you will arrive they will read   I will be writing you will be sleeping he will be running we will be thinking you will be arriving they will be reading   future II   future II continuous   I will have written you will have slept he will have run we will have thought you will have arrived they will have read   I will have been writing you will have been sleeping he will have been running we will have been thinking you will have been arriving they will have been reading

simple past   simple past continuous   I wrote you slept he ran we thought you arrived they read   I was writing you were sleeping he was running we were thinking you were arriving they were reading   present perfect*   present perfect continuous   I have written you have slept he has run we have thought you have arrived they have read   I have been writing you have been sleeping he has been running we have been thinking you have been arriving they have read   past perfect   past perfect continuous   I had written you had slept he had run we had thought you had arrived they had read   I had been writing you had been sleeping we had been running we had been thinking you had been arriving they had been reading

* actually the present perfect is a present tense but for the purpose of this overview it is put into the table of past tenses. To be exact it is the connecting link between the past and the present.

With the examples above you see there are - sometimes quite subtle - differences between the different tenses. The same applies also to the Spanish tenses even if it's unfortunately not possible to transfer them 1:1. One main difference is that Spanish has two past tenses (pretérito imperfecto and pretérito indefinido) where English has only one (simple past).

When having a look at the conjugations in Spanish we had the conjugation in the present tenses of verbs ending with -ar, -ir and -er, remember?

-ar   habl-o   habl-as   habl-a   habl-amos   habl-áis   habl-an

-er   com-o   com-es   com-e   com-emos   com-éis   com-en

-ir   recib-o   recib-es   recib-e   recib-imos   recib-ís   recib-en

Now we'll have a look at the past tenses starting with the simple past, the pretérito imperfecto.