The point system for pieces is some of the most useless things to have. Pieces have a dynamic value that can change a lot by the position. A pawn in 7th row is well worth a piece, a well placed knight is way more powerful than a rook, and on the other hand, a stuck piece in some corner of the board is worth about a pawn or so. Piece activity and positional potential of the piece is what defines it's true value, and it shifts way more than most people might be led to think. I like sacrifices, and often when you sacrifice a piece to get a crucial positional advantage, it's as if your other pieces get an insane boost in "power"/"value"
Chess rating system

The point system for pieces is some of the most useless things to have. Pieces have a dynamic value that can change a lot by the position.
Yea, you right, but those points comes from how well the pieces are dominating the board at their best, i think. how many squares they control. On the other hand the king's value is infinite - you lose it you lose the game, but it is dominating by only eight closest squares (+1 where it is) but queen can dominate at most 29? (=8+7+7+7).

28.
Queen nominate the square where it is too. And supposing there is not the opposite's King in any her square. So: 7 + 7 + 7 + 7 + 1 = 29.

As well as the pieces are not equal in value, I think the victories are not. From chessmate you should get more rating points than from resignation and even different kinds of chessmates should give different kinds of rating points. But of course that is difficult to argue and be automated how much.

IT ALL DEPENDS ON THE POSITION!!!!!!!!!!!
To be eaxact: it depends from the position of the game and position of the piece in that game. So: two position ;)

The point system for pieces is some of the most useless things to have. Pieces have a dynamic value that can change a lot by the position. A pawn in 7th row is well worth a piece, a well placed knight is way more powerful than a rook, and on the other hand, a stuck piece in some corner of the board is worth about a pawn or so. Piece activity and positional potential of the piece is what defines it's true value, and it shifts way more than most people might be led to think. I like sacrifices, and often when you sacrifice a piece to get a crucial positional advantage, it's as if your other pieces get an insane boost in "power"/"value"
Indeed the pieces have dynamic value, but I think the things you mention are way more depending on the position compared to the general value system.
"A pawn in 7th row is well worth a piece", a pawn on the 7th row might be worth about a pawn or worth more than a rook, it is way more dynamic than just calling it worth about a piece.
"A well placed knight is way more powerful than a rook", That depends on how well the knight is placed and on how well the rook is placed that we compare it to. Sometimes trading a rook for a well placed knight is fine, but I would say it is very rare that a knight is worth more than a rook. I think I have never faced a knight that I am willing to trade with more than a rook for (if it doesn't create an immediate threat).
"a stuck piece in some corner of the board is worth about a pawn or so", again it depends a lot on the position. What pawn are we comparing it to? I heard a pawn on the 7th is worth a piece, maybe thats the pawn we are comparing to?
I guess your arguments are valid if your examples uses "can be" instead of "is", but I think the general value system has its merits (far from "the most useless things to have"). It's a good tool to get new players to get an idea of the value of the pieces and I think most players use it as a base and change the dynamic value of the pieces accordingly as the game progresses.

I had a friend that past away this year. He had a higher chess rating than me but he would play chess with me. We had a friendship that went beyond chess ratings. For me chess ratings I view them as an indication of where my chess performance is at the time. Each day I play chess on here, do the chess mentor, and solve a tactical puzzle or two. Each day each of these rating categories goes up and down. For me chess ratings are important as a measurement of current performance showing me how I have improved or not improved but these chess ratings are not all important to me. I take the chess rating system in moderation and not to extremes. There is always someone who is better at a activity or performance than someone else. We are not what we do. I am not my chess rating, a chess rating is a rating of my chess performance but it is not the rating my me or the totality of my personhood.

turtle, the general points system followed is as follows:
pawn - 1pt.
knight/bishop - 3pts.
rook - 5pts.
queen - 10pts.
of course points are not everything... the position of your piece also matters.. for example you might not mind losing a bishop or rook to save a pawn on the 7th row.. and points dont have any bearing on the game result.. it is just a basic framework to help beginners understand the value of different pieces
queen is 9pts!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Samuel, Book 2, Chapter 13, verse 17.

start at 1200.after few months still 1255 something ,consider to use an engine,I prefer my ice cream.would you like some?

hello, i just started here at live chess with rating 1200, but when i start a match i can get up to 215 in rating for a win ?? whats wrong ?? i started at 1200 i won the first match and then got rating 1350 ?? but when i joined a tournement my rating was still 1200 ??
The site uses the Glicko system which has a built in level of uncertainty. Since you haven't played very many games your uncertainty (Rating Deviation or RD) is high and means with any win or loss your rating can change pretty drastically. As you play more games, the RD value will begin to decrease as you get closer to what is your real strength/rating and your changes will become smaller.
As to your other question, each time control has its own rating pool (bullet, blitz, rapid and correspondence/daily). So, the tourney you were looking at joining where you were listed at 1200 was for a pool you haven't played any games in yet.

In playing my first game on Chess.com, I received a rating of 1200, before I played. Why, and how was that arrived at?
Is tactics trainer rating skewed upward? For some reason I usually have about 1500 rating on live chess and the max I ever had was about 1800 at online chess (on another account), but my tactics trainer is a lot higher; I have an average of 2000, which I don't think I'm worth. Anyone else has the same problem?
turtle, the general points system followed is as follows:
pawn - 1pt.
knight/bishop - 3pts.
rook - 5pts.
queen - 10pts.
of course points are not everything... the position of your piece also matters.. for example you might not mind losing a bishop or rook to save a pawn on the 7th row.. and points dont have any bearing on the game result.. it is just a basic framework to help beginners understand the value of different pieces
queen is 9pts!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!