It's highly unlikely that the sellers will accept your offer as it's originally written. Sellers use counter offers to fine-tune the price, terms, and conditions of offers they receive.
Suppose, for example, that you offer $175,000 for a home that you like and you ask to close 30 days after the sellers accept your offer. Because they had the house listed at $189,500, the sellers think that your offering price is a mite low. Furthermore, they need six weeks to relocate.
Instead of rewriting your entire offer, they give you a counteroffer. It states that they're willing to accept all the terms and conditions of your offer except that they want $185,000 and six weeks after acceptance to close.
You don't mind a six-week closing, but you don't want to pay more than $180,000, so you give the sellers a counter-counter offer to that effect.
The sellers come back to you with a firm $184,000. You grudgingly respond at $181,000 and instruct your agent to make it clear to the sellers that you won't go any higher. Two can play the firm game.
If you really want the home, this phase of the game can be nerve-racking. You worry about another buyer making the sellers a better offer and stealing the house away while you're trying to get the price down that last $3,000. The sellers are equally concerned that they'll lose you by pushing too hard for the final $3,000. You don't want to pay a penny more than you have to. The sellers don't want to leave any money on the table. You and the sellers are close to agreement on price. Your offering price and the sellers' asking price are both factually based upon recent sales of comparable houses in the neighborhood. An equitable way to resolve this type of impasse is to split the difference 50-50. The mutual $1,500 concession equals less than 1 percent of the home's fair market value based on a $182,500 sale price.
Splitting the difference won't work in all situations. It is, however, a fair way to quickly resolve relatively small differences of opinion so you can make a deal and get on with your life.