strings are sequences of characters string literals can be delimited with either single or double quotes strings and lists can be manipulated with the built-in sequence operations for concatenation (+)repetition (*)indexing ([])slicing ([:])and length (len() for loop can be used to iterate through the characters of stringitems in listor lines of file one way of converting numeric information into string information is to use string or list as lookup table lists are more general than strings strings are always sequences of characterswhereas lists can contain values of any type lists are mutablewhich means that items in list can be modified by assigning new values strings are represented in the computer as numeric codes ascii and unicode are compatible standards that are used for specifying the correspondence between characters and the underlying codes python provides the ord and chr functions for translating between unicode codes and characters python string and list objects include many useful built-in methods for string and list processing the process of encoding data to keep it private is called encryption there are two different kinds of encryption systemsprivate key and public key program input and output often involve string processing python provides numerous operators for converting back and forth between numbers and strings the string formatting method (formatis particularly useful for producing nicely formatted output text files are multi-line strings stored in secondary memory file may be opened for reading or writing when opened for writingthe existing contents of the file are erased python provides three file reading methodsread()readline(and readlines(it is also possible to iterate through the lines of file with for loop data is written to file using the print function when processing is finisheda file should be closed exercises review questions true/false python string literal is always enclosed in double quotes the last character of string is at position len( )-