A solution is a value that satisfies an equation, makes it true. For example, the equation
x+1=4
has the solution
x=3, since
3 is the only value for
x that makes the equation true. The solution set for an equation can be everything from zero to infinitely many. The equation
x=x+1
has zero solutions since it's impossible to add
1 to a value and get the value itself. An equation can also have infinitely many solutions, like
x+x=2x.
It is possible to enter any value for
x and the equation will be true.