bash print lines that match any of several words

# Basic syntax:
grep first_word input_file | grep second_word
# This finds all lines that contain the first_word and then pipes them
# to a second filter that looks for the second_word, resulting in all
# lines that contain both words. Simply add more pipes and greps to 
# return lines that meet other search criteria. 

# Basic syntax:
grep 'word1\|word2\|word3' /path/to/file
# This prints all lines that match word1, word2, OR, word3

# Basic syntax:
grep -A number word_to_match input_file
# This prints "number" number of lines after and including the first
# line that matches word_to_match in the input_file

# Note, the word_to_match can be any expression that grep uses for 
# 	identifying matches (e.g. including combinations of AND and OR, etc)