Philately is the study of stamps and postal history and other related items. Philately involves more than just stamp collecting, which does not necessarily involve the study of stamps.
Strictly, a philatelist is someone who has an interest or a liking for stamps (and related material), so you don’t even have to be a collector to be a philatelist – but it helps! And it isn’t just about stamps or even postage stamps.
The collection and study of postage stamps became popular in the second half of the 19th Century, and soon came to be called  “philately” (from the Greek “ateleia” meaning “exempt from tax”).

Stamp Collection:

“Stamp collecting” is the accumulation of material related to the payment of postage and the carriage of the mails. In addition to traditional postage stamps, many philatelists — the fancy word for stamp collectors — also collect covers, envelopes that carried mail. Some individuals also collect markings or labels applied to mail including postage meters. Others will even collect Christmas Seals, revenue stamps and other ephemera.

How to collect stamps:

You can collect stamps in many ways.  Some collectors concentrate on the issues from one country, or those issued during a particular period, such as the reign of a monarch or head of state. Other collectors study particular types of stamps, the watermarks of the paper, etc. Talking to other enthusiasts you will learn of the enormous variety and the complexity of stamps. Once you have decided upon your subject, you can begin the hunt for your collection!.

What to Collect?:

Worldwide Collecting — Many people begin collecting everything — worldwide. However, with the countries of the world currently issuing a total of about 10,000 postage stamps each year, unless you have lots of money, lots of space, and lots of time, at some point trying to collect every stamp issued by every country is probably unrealistic.

Country Collecting — Traditionally, collectors would specialize by choosing a single country to collect, most often their home country, the country where they once spent a memorable vacation, or a country whose stamps just look interesting. For a few countries obtaining every stamp issued is possible without having to spend a fortune. However, for most countries there will probably be at least a few stamps that most of us cannot afford. Thus some collectors will narrow their specialty even further, perhaps limiting themselves to used stamps issued since they were born.

Topical Collecting — Another increasingly popular method of collecting is by topic. Topicals give you an opportunity to explore all types of stamps from all over the world. Most are relatively inexpensive and allow you to customize and organize your collection however you want. Think of any topic, and someone probably collects it. Animals, birds, flowers, ships, space, scouts, Disney, and sports are some of the most popular topics. However, exhibits have been put together on much less common topics such as rainbows and even outhouses on stamps.
Topicals are also great in that you can choose what types of material to include. Most topical collectors look for special postmarks that relate to their topic. First day covers and postal stationery also offer great opportunities for topical collections.

Mint or Used — Most people come to prefer either mint stamps — stamps that have never been used and look the way they did when they were sold at the post office — or used stamps — stamps that have served their intended purpose of carrying the mail. An advantage of used stamps is that you do not have to worry about preserving the gum and can use inexpensive stamp hinges to mount your stamps on album pages. Most stamps cost more mint than used, but there are exceptions. Sometimes the cancellations on used stamps are of interest. The choice to collect mint or used or even a mixture of the two is your decision alone.

Collecting By Type — Some individuals collect stamps based on the type of stamps, such as only air mail stamps or only coil stamps. This category may appeal to you if you are interested in stamps used to pay special services such as special delivery or postage due. However, the majority of philatelists collect stamps of all types.

Other Traits — Some collectors prefer to collect stamps of a certain shape or color. Remember there is nothing wrong with creativity. If you see colorful stamps coming in the mail that interest you, collect them. One individual may choose to collect only yellow stamps, another only stamps issued on their birthday, and a third may be working on building a collection with cancels showing numbers with 1 to as high as they can find. The important thing about stamp collecting is not the value of your collection or how many other people collect the same thing, it is that it is fun for you!