A string is an immutable sequence of characters. Methods return new strings and leave the original alone.

• s.strip() removes surrounding whitespace.
• s.split() breaks on any run of whitespace and returns a list.
• "-".join(parts) glues a list back together.
• s.upper(), s.lower() and s[0] do what they look like.

Put f before the quote and expressions inside braces. After a colon you can add a format spec.

name = "Ada"
cost = 3.5
print(f"{name}: {cost:.2f}")
print(f"[{name:<6}]")   # [Ada   ]
print(f"[{cost:>6.2f}]")  # [  3.50]
print(f"{cost = }")     # cost = 3.5

< pads on the right, > pads on the left, and the number is the minimum width. Text longer than the width is not cut.

Python 3.14 also adds t-strings, a template form aimed at libraries. For everyday text, f-strings are the tool.

Write receipt_line(name, price, qty) returning the name padded to width 10, a space, x and the quantity, a space, then price * qty right-aligned in width 7 with 2 decimals. Write initials(full_name) returning the upper-case first letter of each word.

The explanation opens here once every check passes.