When you say something, you speak words.

You use say in expressions such as I would just like to say to introduce what you are actually saying, or to indicate that you are expressing an opinion or admitting a fact. If you state that you can't say something or you wouldn't say something, you are indicating in a polite or indirect way that it is not the case.

You can mention the contents of a piece of writing by mentioning what it says or what someone says in it.

If you say something to yourself, you think it.

If you have a say in something, you have the right to give your opinion and influence decisions relating to it.

You indicate the information given by something such as a clock, dial, or map by mentioning what it says .

If something says something about a person, situation, or thing, it gives important information about them.

If something says a lot for a person or thing, it shows that this person or thing is very good or has a lot of good qualities.

You use say in expressions such as I'll say that for them and you can say this for them after or before you mention a good quality that someone has, usually when you think they do not have many good qualities.

You can use say when you want to discuss something that might possibly happen or be true.

You can use say or let's say when you mention something as an example.

Say is used to attract someone's attention or to express surprise, pleasure, or admiration.

If you say that something says it all, you mean that it shows you very clearly the truth about a situation or someone's feelings.

You can use 'You don't say' to express surprise at what someone has told you. People often use this expression to indicate that in fact they are not surprised.

If you say there is a lot to be said for something, you mean you think it has a lot of good qualities or aspects.

If you say that someone doesn't have much to say for himself or herself, you mean that they are not speaking very much during a conversation.

If someone asks what you have to say for yourself, they are asking what excuse you have for what you have done.

If something goes without saying, it is obvious.

When one of the people or groups involved in a discussion has their say, they give their opinion.

You use 'Say what you like about someone or something' when you are about to mention one good thing about a person or thing that many people do not like.

You use 'I wouldn't say no' to indicate that you would like something, especially something that has just been offered to you.

You can use not to say when adding a stronger or more extreme description than the one you have just used.

You use to say nothing of when you mention an additional thing which gives even more strength to the point you are making.

You use shall I say and shall we say in order to warn someone that what you are about to say may cause offence or be surprising.

You use that is to say or that's to say to indicate that you are about to express the same idea more clearly or precisely.

You can use 'You can say that again' to express strong agreement with what someone has just said.