The only time to even think about this question is if you would like your website to attract sales or interest from clients who do not know you and are searching for your goods or services over the internet. If your website is just an information service for existing customers then the answer is already a straight forward no, you require no Online Marketing.
If you do wish your website to work that way then you must establish if you need optimization, or if your site is good enough in that arena already. The best place to begin your research is with your competitors and their placing, in comparison to you, on the internet search engine results listing.
Choose your typical internet search engine, think about your industry and come up with a few quite specific words or phrases that describe loosely what products or services you offer. Then type these into the search engine one at a time and make a note of which of your competitors are usually listed on that first page of results. Also examine each page in turn until you locate your own website details ( if this does not appear after the first 10 pages of results you can stop searching!).
At this position you will be able to assess if your position is a lot lower that the competitors or not. If not, and you are listed up there on page 1 of the results then either you have a quite specific offering, practically no competitors or your site is already optimized to the precise level. Do double check at this point that you have not chosen a very specific keyword or phrase for your trial as this will twist results dramatically and give you a guarantee good Search Engine Placement!
If you have found your website way down the listings, or indeed you have not located your site at all in the first 10 pages then some online promotion in the form of search engine optimization may be worth doing.
There are professional firms out there who will help you to improve your positioning in the search results and this is critical for a decent amount of business. All the firms currently sitting on page one of the search results will attract the attention of at least 85% of the searching clients and provided that they do actually offer what their potential customer wants they will almost definitely get the business. The customer will certainly not be ploughing through page after page of search results when his product is right there on page one.
The Search Engine Optimization Company can ensure that your positioning improves over the course of a month or two and the benefits should then make themselves obvious.