A script is a series of instructions written in a "plain text" file. The script interpreter (for example, Bash or another shell, Python, Perl, Ruby, etc.) reads the file and carries out the instructions as if they had been entered at the command prompt.
A script is a program or sequence of instructions that is interpreted or carried out by another program rather than by the computer processor, in contrast to a compiled program.
A Linux system contains many scripts, especially shell scripts, used to carry out basic tasks, such as package management and updating configurations. Bash and Dash shells, Awk, Python and Perl are some of the commonly used script interpreters/languages used in Ubuntu. For users, writing scripts makes it possible to achieve complex tasks and automate simple ones.