when at the desire of the promisor ,the promisee or any other person has done or abstained from doing or does or abstains from doing ,or promises to do or to abstain from doing something,such act or abstinence or promise is called a consideration for the promise.

Simply it means the consideration the promisor wants from the promisee.

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Firstly paraphrase it,

"When at the desire of the promisor:

i. The promisee (or any other person) has done something [refers to past consideration]
ii. The promisee has abstained from doing something [refers to past consideration]

iii.The Promisee does something [refers to present consideration]
iv. The promisee abstains from doing something [refers to present consideration]

v. The promisee promises to do something [refers to future consideration]
vi. The promisee promises to abstain from doing something [refers to future consideration]

is called consideration for a promise"

The above are six different situations which can form consideration of a promise.

Consideration for a promise may have been received in past, or simulaneously at the time of making promise or in future. For example, when at the request of a Mr. A (the promisor) you keep his book in custody and later after taking it back, he promises to pay your Rs.500 for keeping it safe, it will be a past consideration as the consideration of safe custody had already been received before contracting to pay Rs.500. The words "has done" denotes such past consideration.

When an insurance company says it will indemnify in the event of loss, it is a future consideration. The words "promises to do" refers to such furture consideration

Consideration not only mean a positive act for someone but also abstinence from some act is consideration. For example, PEPSI gives a referigerator to a shopkeeper on the promise that it will not keep product of Coka Cola at his shop. The shopkeeper promises to abstain from keeping Coka Cola products (a future consideration involving abstinence)

In the beginning the words at the desire of promisor are used. These words have their own significance. M.C. Shukla on page 27 of its book titled "Mercantile Law" has explained it by a very good example; if A notices B's house being on fire and rushes voluntarily to B's help, there is no consideration. If however, A goes to B's help at B's desire , there is good consideration. [Note that under former case where there is no consideration if B promises to pay Rs.1,000 for A's voluntary efforts it will be contract without consideration however, it will be valid under section 25 of the Contract Act,]

Also note that consideration may be received by promisee or any other person. For example on page 27 of M.C. Shukla's book; Ms. A gifts his property to her daughter with direction to pay annuity to Ms. A's brother. Accordingly, A's brother & A's daughter also entered into promise that she will pay annuity to him but did not pay later. A's brother sued her daughter for default in payment of annuity. A's Daughter was of the view that she has received no consideration from A's brother hence there is no valid contract between her & A. HOWEVER, it was held that consideration moved from A , though not from promisee (A's brother). That was sufficient consideration for daughter's promise to A.

very well explained

v.wel explained sir