Try this:

1dollar bill equals $1.

4 quarters equal $1.

10 dimes equal $1.

20 nickels equal $1.

100 pennies equal $1.

So sometimes you have different coin worth different amounts and depending on how many of each coin you have they can add up to $1.

BTSX and bitUSD are similar in this same way.

BTSX are the coins that can add up to 1 bitUSD. The only difference is that people get to decide how much value BTSX has every day, hour, minute and second relative to a dollar. Thus, BTSX will constantly be changing from a "Penny" coin one day, to a "quarter" coin on some other day.

For example:

2 days ago, 115 BTSX equaled 1 bitUSD (approximations)

Yesterday, 33 BTSX equaled 1 bitUSD

Today, 40 BTSX equals equals 1 bitUSD

Here is the kicker: 1 bitUSD always equals $1.