Strings and lists are the most commonly used data structures in Python. Strings handle text; lists handle ordered collections. Both support indexing, slicing, and iteration — essential for data processing.
Strings: immutable sequences of characters. Create: s = "Hello" or s = 'Hello'. Indexing: s[0] = "H", s[-1] = "o". Slicing: s[1:4] = "ell", s[:3] = "Hel", s[2:] = "llo", s[::2] = "Hlo". Methods: s.upper(), s.lower(), s.capitalize(), s.title(), s.find("ll") → 2, s.replace("H","J") → "Jello", s.split() → list, " ".join(list) → string, s.strip() removes whitespace. Strings are immutable — methods return new strings, original unchanged.
Lists: mutable ordered sequences. Create: nums = [1, 2, 3], mixed = [1, "hello", True]. Indexing and slicing: same as strings. Modify: nums[0] = 10. Methods: append(item) — add to end, insert(index, item) — add at position, remove(item) — remove first occurrence, pop(index) — remove and return, sort() — ascending order, reverse(), extend(list2) — add all items. List comprehension: squares = [x**2 for x in range(10)]. Iterate: for item in list. Length: len(list). Check: item in list → True/False.
Both are sequences (ordered, indexable, sliceable). Key differences: (1) Strings contain only characters; lists can contain any data type (numbers, strings, other lists). (2) Strings are immutable — "hello"[0] = "H" causes error. Lists are mutable — [1,2,3][0] = 10 works. (3) String methods are text-specific (upper, split, find). List methods are collection-specific (append, sort, pop). Python design: immutability makes strings safe for use as dictionary keys and ensures data integrity.
Book a Trial + Diagnostic session. Get a personalized Learning Path with clear milestones, tutor match, and a plan recommendation — all within 24 hours.
Book Trial + Diagnostic →