We want you to know

Before adding price and define occupant type I am sure you already add room type / define room availability and closeout date, add rate and rate starting date and ending date (You may also add multiple rate under one room based on room availability and closeout date)

Lets think you have a room called "Single room with AC" under single room type. And you have 10 Available room. And during define room availability and closeout date you define:

Available date start from: 1st January 2015
Closeout date: 28th February 2015

Now lets think you want to add 4 different rate for this room (Single room with AC)

Rate A - Single room with AC = From 1st January 2015 to 15th January 2015
Base price is 100 USD and you also add 150 USD for sunday under price by day field.

Rate B - Single room with AC = From 16th January 2015 to 31st January 2015
Base price is 120 USD and you don't define any price for price by day

Rate C - Single room with AC = From 1st February 2015 to 15th February 2015
Base price is 250 USD and you also add 280 USD for sunday under price by day field.

Rate D - Single room with AC = From 16th February 2015 to 28th January 2015
Base price is 150 USD and you also add 180 USD for sunday and 160 for Monday under price by day field.

When and How Rate A will be work:
So if guest book this room for between 3rd January 2015 to 10th January 2015 HBS will be pick Rate A
Base price for Rate A is : 100 USD
and Sunday price is: 150 USD
So guest search for 3rd January 2015 to 10th January 2015
How many Sunday we have from 3rd January 2015 to 10th January 2015 ? Only 1 Sunday.
How many day guest want to booking: 8 Days
So how HBS calculate price: 7 days from base price (700 USD) and 1 day from Sunday price (150 USD)
So total 8 Days price is: 850 USD

When and How Rate B will be work:
So if guest book this room for between 18th January 2015 to 20th January 2015 HBS will be pick Rate B
Base price for Rate A is : 120 USD
and Day price is: Blank
So guest search for 18th January 2015 to 20th January 2015
There we don't have to check any day price because during adding price in rate you keep it blank
How many day guest want to booking: 3 Days
So how HBS calculate price: 3 days from base price (360 USD)
So total 3 Days price is: 360 USD


When and How Rate C will be work:
So if guest book this room for between 3rd February 2015 to 5th February 2015 HBS will be pick Rate C
Base price for Rate A is : 250 USD
and Sunday price is: 280 USD
So guest search for 3rd February 2015 to 5th February 2015
How many Sunday we have from 3rd February 2015 to 5th February 2015 ? No Sunday or day price between guest booking date.
How many day guest want to booking: 3 Days
So how HBS calculate price: 3 days from base price (750 USD)
So total 3 Days price is: 750 USD

When and How Rate D will be work:
So if guest book this room for between 21st February 2015 to 24th February 2015 HBS will be pick Rate D
Base price for Rate A is : 150 USD
and Sunday price is: 180 USD
      Monday price is : 160 USD
So guest search for 21st February 2015 to 24th February 2015
How many Sunday and Monday we have from 21st February 2015 to 24th February 2015 ? Only 1 Sunday -1 Monday
How many day guest want to booking: 4 Days
So how HBS calculate price: 2 days from base price (300 USD) and 1 day from Sunday price (180 USD) and 1 Day from Monday Price (160 USD)
So total 4 Days price is: 640 USD

What is Base Price:
Base price is standard price for hotel room. When you define a rate for specific timeline base price is a default price for that rate time line. 

What is day price: 
Day price is fixed price with in that day during specific rate starting and ending time. So if you add any price for any day its change base price for that specific day.