grep is capable of color-highlighting the matched string in its output. But, by default, that option is turned off.
$ grep abc a_file.txt
There are 3 color options available to you:
Linux only: This is an excellent tip that changes the prompt to red when using the root account from the terminal—as a reminder to be more careful. Using the tip is relatively simple—just edit the /root/.bashrc file and add in the following, preferably commenting out the existing lines that set the color, though you can simply add this line to the end of the file.