The name attribute in the html is the key in the params hash

The params function is a gumball machine that, I theorize, takes in a quarter that is in fact a raw html form.  Inside the params function, I assume there are little elves that take apart the form. The form is a box with lots of boxes inside boxes, like some mysterious woodworker had a lot of time on his hands.  Several of the boxes are labeled input. Inside those input boxes are boxes labeled name.  The elves take out the boxes labeled name and look inside.  Inside is a bunch string with a bunch of letter beads strung on it, like kid's frendship bracelets with their names spelled out. The elves take out another set of safe boxes.  Each of those save boxes has a lock. On that lock is a key.  The elves copy the text from the friendship bracelet onto the key. They look in the mysterioys wooden box again. Right next to where they got the boxes labeled 'name', they find boxes labeled value.  They take the box labeled value, open it up, take out the friendship bracelet inside, and stuff it inside the safety deposit box. When a safety deposit box is full, they shove the box into a bag that smells like hash-browns.  They stick the bag inside a gumball and send it out the door.
Underlined the words that need analogies
Input values to array of values

The elves look into the input box and see a label square brackets
at the end of the label. For example

 name = "stingray[]"

The elves know that when they see a name with square brackets, they are
supposed to copy the name to a single safety deposite box.  They then
take the friendship bracets out of every value box that is inside an
input box with the name stingray.  They stick every friendship bracelet
inside a pillbox. Each bracelet gets it's own compartment in the pillbox.
Then the elves stick the pillbox in teh safety deposite box, stick the
box in a bag, wrap the box in a gumball, and shove it out the door to
the waiting gumball buyer.
How a value is placed in the params hash depends on its name

The elves are much smarter than I am. I can only focus effectively on
one job at once. When they identify different labels, they have absolutely
no problem interpreting those effectively and choosing whether to stick
the valuable things directly inside a safety deposit box, or whether
to stick the valuable things inside a pillbox and then inside the
safety deposit box.
Parsing multiple input values into a hash

When the elves see, inside the name box, a label with square braces that has a word inside the square braces, like

name="swordfish[benny]"

They write swordfish on the key of the safety deposit box. They write benny
on the key of another, smaller safety deposit box. They grab the valuable
jewels from the box labeled value and stick them inside the smaller safety deposit box.  They put the smaller safety deposit box in the larger
safety deposit box. Then they stuff the larger safety deposit box in a bag, stick the bag inside a gumball, and push it outside the gumball-machine's door.
You can nest arrays inside the hashes

The elves have recieved a new wooden puzzle box and are getting more and more experienced at handling strange cases. When they see two sets of square braces on a name box, like

name="sharkbait[nemo][]"

they take out two sets of safety deposite boxes and a pillbox. They write sharkbait on the key to the biggest safety deposit box.  They write nemo on the key to the smaller safety box.  They take out a valuable thing from the values wooden box.  I imagine it's a set of earrings.  They stick the earrings in the pill box.  They stick the pillbox in teh small safty deposit box. The stick the small safety deposit box in the large safety deposit box. They stick the box in a bag.  They stick the bag in a gumball and shove it out the door.
Putting a hash inside an array inside a hash

The elves have recieved their final wooden box.  They open the boxes within the boxes, and they see a name that looks like this:

  name=sharkbait[][nemo]

They get out a safety deposit box, a large pillbox, and another safety deposit box that fits inside one cell of the pillbox.  They write sharkbait on the key to the large safety deposit box.  They write 1 on one of the cells of the pillbox.  They write nemon on the key to the small safety deposit box. They get a set of earrings from the values box and stick them in the small safety deposit box, stick the small safety deposit box into the pillbox named 1, and stick the pillbox in the large safety deposite box, stick the large safty deposite box in a bag, stick teh bag in a gumball, and roll the gumball out the door.