If something is for someone, they are intended to have it or benefit from it.

If you work or do a job for someone, you are employed by them.

If you speak or act for a particular group or organization, you represent them.

If someone does something for you, they do it so that you do not have to do it.

If you feel a particular emotion for someone, you feel it on their behalf.

If you feel a particular emotion for someone or something, they are the object of that emotion, and you feel it when you think about them.

You use for after words such as 'time', 'space', 'money', or 'energy' when you say how much there is or whether there is enough of it in order to be able to do or use a particular thing.

If something is for sale, hire, or use, it is available to be sold, hired, or used.

You use for when you state or explain the purpose of an object, action, or activity.

You use for after nouns expressing reason or cause.

You can use for to introduce a clause which gives the reason why you made the statement in the main clause.

You can use for to introduce the cause of the fact that you have just mentioned.

For is used in conditional sentences, in expressions such as 'if not for' and 'were it not for', to introduce the only thing which prevents the main part of the sentence from being true.

You use for to say how long something lasts or continues.

You use for to say how far something extends.

If something is bought, sold, or done for a particular amount of money, that amount of money is its price.

If something is planned for a particular time, it is planned to happen then.

If you do something for a particular occasion, you do it on that occasion or to celebrate that occasion.

If you leave for a particular place or if you take a bus, train, plane, or boat for a place, you are going there.

You use for when you make a statement about something in order to say how it affects or relates to someone, or what their attitude to it is.

After some adjective, noun, and verb phrases, you use for to introduce the subject of the action indicated by the following infinitive verb.

You use for when you say that an aspect of something or someone is surprising in relation to other aspects of them.

If you say that you are for a particular activity, you mean that this is what you want or intend to do.

If you say that something is not for you, you mean that you do not enjoy it or that it is not suitable for you.

If it is for you to do something, it is your responsibility or right to do it.

If you are for something, you agree with it or support it.

You use for after words such as 'argue', 'case', 'evidence', or 'vote' in order to introduce the thing that is being supported or proved.

For is the preposition that is used after some nouns, adjectives, or verbs in order to introduce more information or to indicate what a quality, thing, or action relates to.

To be named for someone means to be given the same name as them.

You use for with 'every' when you are stating a ratio, to introduce one of the things in the ratio.

You can use for in expressions such as pound for pound or mile for mile when you are making comparisons between the values or qualities of different things.

If a word or expression has the same meaning as another word or expression, you can say that the first one is another word or expression for the second one.

You use for in a piece of writing when you mention information which will be found somewhere else.

If you say that you are all for doing something, you agree or strongly believe that it should be done, but you are also often suggesting that other people disagree with you or that there are practical difficulties.

If you are in for it or, in British English, if you are for it, you are likely to get into trouble because of something you have done.

You use expressions such as for the first time and for the last time when you are talking about how often something has happened before.