The Three Concepts of Prayer - Praise, Supplication and Acknowledgement.

Here is how Rambam describes the mitzvah of Tefilah in Mishne Torah:

מצות עשה להתפלל בכל יום, שנאמר "ועבדתם, את ה' אלוהיכם"
מפי השמועה למדו שעבודה זו--היא תפילה, ונאמר "ולעובדו, בכל לבבכם
אמרו חכמים, איזו היא עבודה שבלב, זו היא תפילה. ואין מניין התפילות מן
התורה, ולא משנה התפילה הזאת מן התורה. ואין לתפילה זמן קבוע מן התורה

It is a positive commandment to pray daily as it says, “Worship Hashem your God”. Tradition [generally, when Rambam uses this term it refers to the explanation that Moshe received together with the written text] teaches that this worship is prayer as it also says, “and to worship Him with all your heart”; the Rabbis said one worships from the heart through prayer. [The point is that worship is a matter of the heart [in biblical parlance the mind] which is expressed in prayer]. Neither the number of prayers, nor the language of the prayer, nor the time of prayer [are set] biblically. (Hil Tefilah 1:2)

Unlike other Mitzvot that have clearly defined parameters on how they are to be performed, prayer is loosely defined as meditation, עבודה שבלב- worship from the heart, which is expressed. There is neither a specific template nor even a set time; one can pray all day or just once for a short time. However, the conceptual content of prayer is defined by the rabbis. This was defined in two steps. From the time of Moshe until the times of Ezra [the Return from Bavel], there was only a rough outline of what the prayer should contain.

אלא חיוב מצוה זו, כך הוא--שיהא אדם מתפלל ומתחנן בכל יום, ומגיד שבחו
של הקדוש ברוך הוא, ואחר כך שואל צרכיו שהוא צריך להן בבקשה ובתחינה, ואחר
כך נותן שבח והודיה לה' על הטובה שהשפיע לו: כל אחד כפי כוחו.
אם היה רגיל, מרבה בתחינה ובקשה; ואם היה ערל שפתיים, מדבר
כפי יוכלו ובכל עת שירצה. .

The obligatory performance of this Mitzvah is thus; one should pray and implore daily. [First] one should declare the praise of HKBH, thereafter one should supplicate and implore for ones’ needs and thereafter give praise and thank God, for all the good He bestowed on him. If fluent, one would be profligate with the imploration and supplication. If, on the other hand, one were tongue tied, he would speak as well as he could and at any time one so wished.

As opposed to the other kind of prayer, the prayer required when one encounters difficulties, this prayer requires us to look to the future in context of the past. We are commanded to contemplate how everything we hope to get and accomplish, all our needs, is the result of God’s will. One begins by expounding on our awareness of God through His actions, our perception of him in our existence as the First Cause. Having internalized this idea, we now turn to all the things we are planning to do going forward and place them in that context. Whether we are doing things for ourselves or for the community, we want to make sure that we are doing them in a way that falls in line with God and His ways. When we supplicate and implore God, we are saying we want to do what is right, we therefore want to get as close as possible to You and sublimate our personal wants to the greater goal that You set for our existence. We are in a quandary about what we are about to do; we are not sure we are doing the right thing. But we do have to act and decide how to move forward. We remove ourselves from the equation and try to see everything from God’s point of view. We express this quandary and insecurity through supplication. We then close with an acknowledgement that God is ultimately responsible for all the good things that we have so far. As we will see when we discuss the second phase of prayer, from the time of Ezra onward, the Rabbis fleshed out these components of prayer very clearly.