You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention relates to the general art of showers, and to the particular field of showerheads. 
       BACKGROUND OF THE INVENTION 
       [0002]    The shower bath has an ancient history, with paintings on ancient Greek vases showing that there were shower baths employing advanced systems of water supply and drainage by the fifth century, B.C. In Roman times, the bather was anointed with oil before his bath to reduce the tendency of the skin to dry out after bathing. The shower bath has survived into modern times and has become so common in usage that bathrooms in domestic households generally include a shower nozzle mounted from the wall above the bathtub. The common method of a person taking a shower is to have plain water flow through the shower head onto the person&#39;s body, with the person applying the soap by hand or brush to the person&#39;s body. 
         [0003]    Conventional bathing techniques in the usual shower stall are accompanied with certain difficulties and inconveniences which it is a primary purpose of the present invention to overcome. For example, a not unusual occurrence is for the bather to have difficulty locating and retaining bar soap, which can fall from a receptacle onto the floor of the shower stall, not only making it difficult to find, but also hazardous to the bather. Another frequent occurrence is that the bar soap may be allowed to reside in a receptacle also containing water which wastes the soap. 
         [0004]    As a convenience to bathers there is need for a device to soap the water issuing from a shower head so that the bather will not have to handle a wet and slippery bar of soap. By applying the soap directly to the shower spray, the bather may soap his whole body very quickly and efficiently and then, by merely turning a valve, shut off the soapy water and turn on clear water to wash the soap off his body. With such a device, the soap is handled in dry condition and only when it becomes necessary to insert a new bar of soap into the soap chamber of the device. 
         [0005]    However, the inventor is not aware of any device which fulfills these needs in an efficient and economical manner. In particular, the replacement of soap after a supply has been exhausted is often a difficult and onerous task. 
       SUMMARY OF THE INVENTION 
       [0006]    The above-discussed disadvantages of the prior art are overcome by a showerhead which includes a built-in soap dispenser that allows water and liquid soap to mix inside and emerge simultaneously to provide lather from the showerhead. The soap is contained in a cartridge which is clipped to the showerhead. 
         [0007]    Other systems, methods, features, and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the invention, and be protected by the following claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0008]    The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views. 
           [0009]      FIG. 1  is a perspective view of a soap-dispensing showerhead embodying the present invention. 
           [0010]      FIG. 2  shows a soap cartridge for use in the showerhead of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]    Referring to the figures, it can be understood that the present invention is embodied in a showerhead unit  10  which comprises a showerhead  12 . Showerhead  12  includes a first end  14  that is a water inlet end and which is fluidically connected to a source of water and a second end  16  which is a showerface and which has a multiplicity of water outlet ports, such as water outlet port  18 , defined therethrough through which water W from the inlet end passes during use of the showerhead. A body  20  fluidically connects first end  14  of the showerhead to second end  16  of the showerhead. 
         [0012]    A fluid port  30  is defined through the body of the showerhead. Fluid port  30  is in operational fluid communication with water passing through the body of the showerhead so that water flowing through the body of the showerhead flows into and out of the fluid port. 
         [0013]    A soap container unit  40  is mounted on body  18  of the showerhead and includes a fluid flow port  42  which is fluidically connected to fluid port  30  to be in fluid communication with water flowing through the body of the shower head so that water flowing through the body of the showerhead flows into and out of fluid flow port  42  via fluid port  30 . Fluid flow port  42  of the soap container unit includes an inlet section  44  and an outlet section  46 . A one-way valve  48  is included on inlet section  44  and a one-way valve  50  is included on outlet section  46  so fluid flows into the soap container via fluid flow port  30  and via fluid port  42  from body  18  of the showerhead via inlet section  44  and out of fluid port  30  via fluid flow port  42  back into body  18  of the showerhead via outlet section  46 . 
         [0014]    Alternatively, the liquid soap in the soap container unit  40  may be drawn into the body  20  of the showerhead unit  10  through the air flow port  42 . As water passes through the body  20 , lower pressure may be created within the body relative to the atmosphere. As such, the liquid in the soap container unit  40  may be drawn into the body  20  through the air port  42 . The soap container unit  40  may have an air inlet opening  62  so that vacuum does not get created within the soap container unit  40  or to substantially maintain an atmospheric pressure within the soap container. 
         [0015]    A connection element  60  on the soap container connects the soap container to the body of the showerhead with fluid flow port  42  of the container unit in fluid communication with fluid port  30  of the showerhead. The soap container unit  40  may include soap in a liquid form which can be refilled when necessary. The soap container unit  40  may have a triangular configuration where the connection element  60  is located in one of the three corners of the triangular shaped soap container  40 . In the mounted position, the connection element  60  may be on the bottom side of the soap container unit  40  to allow the liquid soap to drain through the connection element  60 . Alternatively, the showerhead unit  10  may be provided with replaceable soap container units  70 ,  72 , and  74  to replace the soap container unit  40  when it is empty. 
         [0016]    While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of this invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.

Summary:
A showerhead includes a built-in soap dispenser that allows water and liquid soap to mix inside and emerge simultaneously to provide lather from the showerhead. The soap is contained in a cartridge which is clipped to the showerhead.