English Idioms and Idiomatic Expressions 

Idioms: Knowledge and Wisdom
from: 'common knowledge'   to:  'wise for their years'

• common knowledge
  • Common knowledge is information that is well-known to everyone.
    “The intern is Jack’s son – I thought that was common knowledge!”
    
    
• know better than to do something
  • If you know better than to do something, you are experienced or wise enough not to do it.
    "You should know better than to go sailing in stormy weather."
    
    
• know someone inside out
  • If you know someone inside out, you know them very well.
    "Sue and Anne have been friends since childhood. They know each other inside out."
    
    
• know something like the back of your hand
  • If you know something like the back of your hand, you are very familiar with it or know it in detail.
    "Of course I won't get lost. I know London like the back of my hand!"
    
    
• know your onions
  • A person who knows their onions is very knowledgable about a particular subject.
    "If you need more information on the subject, Sam is the best person to ask. He really knows his onions!"
    
    
• know the ropes
  • Someone who knows the ropes is familiar with the way something is done or knows how to do it.
    “Charlie can fill in for Sam. He knows the ropes."
    
    
• know the score
  • If you know the score you are well-informed about a situation and know what to expect.
    “If Laura damages the car, her dad won't lend it to her again. She knows the score."
    
    
• know which side your bread is buttered
  • If you know where your interests lie or what will be to your advantage, you know which side your bread is buttered.
    “Paul never argues with his father-in-law because he knows which side his bread is buttered."
    
    
• know which way the wind is blowing
  • If you know which way the wind is blowing, you know how a situation is developing and can prepare for any changes or potential problems.
    "Before we decide, we need to know which way the wind blowing.”
    
    
• know your onions
  • Someone who knows their onions is very knowledgeable or well-informed about a particular subject.
    "When it comes to the new tax reform, the new accountant really knows her onions."
    
    
• know your own mind
  • If you know your own mind, you know what you want or like, and are capable of making a decision.
    "I don't want to influence you. You're old enough to know your own mind."
    
    
• knowledge is power
  • This expression means that the more knowledge you have, the better your chances are of being successful, or the more control you will have over your future.
    
    
• read from the same page / be on the same page
  • People who read from the same page or who 'are on the same page' share the same understanding or knowledge about something, or have the same opinion as others in a group.
    "We need to be reading from the same page before we talk to the boss."
    
    
• sing from the same hymn book
  • Similar in meaning to 'read from the same page'.
    It means to think in the same manner, have the same opinion or say the same thing about something as other people.
    
    
• stay in the loop/stay in the know
  • If you stay in the loop or stay in the know, you are informed about the most recent developments or are aware of what is happening.
    "Make the sure the new intern stays in the loop about the project.”
    
    
• street smart/street wise
  • A person who is street-smart or streetwise has enough experience and knowledge about life in the city to be able to deal with difficult or dangerous situations.
    "The kids living in this area are all street-smart - they're in less danger than us."
    
    
• tech savvy
  • People who are tech savvy have sufficient technical knowledge and skills to be comfortable using computers and other electronic devices.
    "Many students are more tech-savvy than their teachers."
    
    
• (a) walking encyclopaedia
  • This term refers to a person who is very knowledgeable about a lot of subjects.
    "The origin of Halloween? Ask Jill - she's a walking encyclopaedia!"
    
    
• get wise to something
  • If you get wise to something, you learn something that you were not aware of before.
    "The old man finally got wise to the fact that children were stealing apples from his garden."
    
    
• wise for their years / wise beyond their years
  • Someone who is wise for their years or wise beyond their years has more knowledge and experience that most people at their age.
    "She's still a child but she's wise beyond her years."