Answer:variables - placeholders for important values
# used to avoid recomputing values and to
# give values names that help reader understand code
# valid variable names - consists of letters, numbers, underscore (_)
# starts with letter or underscore
# case sensitive (capitalization matters)
# legal names - ninja, Ninja, n_i_n_j_a
# illegal names - 1337, 1337 ninja
# Python convention - multiple words joined by _
# legal names - elite_ninja, leet_ninja, ninja_1337
# illegal name 1337_ninja
# assign to variable name using single equal sign =
# (remember that double equals == is used to test equality)
# examples
my_name = "Joe Warren"
print my_name
my_age = 51
print my_age
# birthday - add one
#my_age += 1
print my_age
# the story of the magic pill
magic_pill = 30
print my_age - magic_pill
my_grand_dad = 74
print my_grand_dad - 2 * magic_pill
Explanation:placeholders for important values. 2. # used to avoid recomputing values and to. 3. # give values names that help reader understand code. 4. . 5. .