The Quick Rule
Use as when two things are equal, than after a comparative adjective, and like when something resembles something else. My car is as fast as his uses "as" because they are equal in speed. My car is faster than his uses "than" because you are comparing one thing as superior. He drives like a professional uses "like" because you are saying his driving resembles a professional's style.
When Do You Use "As"?
You use "as" in the pattern "as + adjective + as". This structure tells the listener that two things are the same in some way. Your English is as good as mine. This coffee is as hot as that one. The building is as tall as the one next door. Notice that "as" appears twice, and an adjective sits between them. The rule holds whether the adjective is short (fast, tall, good) or longer (expensive, beautiful, interesting). If you want to say two things are equal, "as" is your word.
When Do You Use "Than"?
You use "than" only after a comparative adjective. A comparative adjective is one that ends in "-er" or uses "more": faster, slower, taller, more expensive, more beautiful. My car is faster than his. English grammar is more confusing than I thought. This restaurant is cheaper than the one on the corner. "Than" introduces what you are comparing the first thing to. You cannot say "faster as" or "more beautiful as". The structure is always comparative + than.
When Do You Use "Like"?
You use "like" to mean "similar to" or "in the manner of". He plays like a champion. She sings like an angel. Your writing style is like mine. "Like" does not create a true comparison of degree. You are not saying one thing is more or less of a quality. You are saying one thing resembles or imitates another. In conversation, people also use "like" very casually ("I was like, wow"), but in clear English writing and speech, stick to the "similar to" meaning.
The Most Common Mistake
English learners often mix "as" and "like" because both can suggest similarity. But "as" in the "as...as" structure is specifically for equal things, while "like" means resemblance. Do not say "He is like as tall as me". Say either "He is as tall as me" (they are equal height) or "He is like me in height" (he resembles me). This distinction matters because listeners will notice the difference.
Practice With Real People, Not Just Rules
Knowing the rule is one thing. Using it naturally in conversation is another. Most English learners can recite the grammar but stumble when someone is actually talking to them. This is where speaking with native speakers changes everything. When you practise with a real person, they ask follow-up questions, they use these structures in unpredictable ways, and your brain learns faster because you need the words to express yourself right now.
PBC Languages runs free language exchanges with native English speakers, paired just for conversation. These exchanges have no lesson plan and no cost. You and your partner trade your languages, help each other, and you end up using structures like "as", "than", and "like" without thinking about the rule. The grammar sticks because you are solving real communication problems. If you want a more structured approach, PBC also offers live classes in tiny groups (maximum 4 students), so you actually get time to speak and be corrected gently by an experienced teacher. The first class is free. Between classes, WhatsApp groups keep your English alive with daily conversation and cultural exchanges.
Language lives between people, not in a textbook. Get the grammar right first, then test it with someone who speaks it every day.