Similarity in psychology means being alike or sharing common features with someone else or something else. It's like when you see someone who likes the same toys or cartoons as you and you think, "Wow, we're just alike!" People can be similar in many ways, like having the same hair color, wearing similar clothes, or having the same interests. When you feel like someone is similar to you, it can make you feel good and help you bond with that person. It's like you have a special connection with them. Sometimes, we might even prefer people who are similar to us because we think they will understand us better and we will be more comfortable around them.