Increasing or decreasing the pitch will speed up or slow down the bpm accordingly. Every turntable can be tuned according to a DJ's preferences. You can add slipmats, adjust the tonearm weight, height, anti-skate setting, and most importantly choose the cartridge and stylus. The cartridge system determines the sonic quality and tracking ability, ensuring great sound and less skips during playback, or while cueing or scratching a record. While these look like normal connectors you might find attached to tape decks or CD players, they carry a low signal level that needs to be raised to a standard line level with a preamplifier usually found in DJ mixers or turntable-ready home receivers.
All companies make various models each with different input, output, and effects capabilities.
There are battle mixers for performance DJs, and even mixers with built-in equalizers and samplers. Numark DM-1150 shown above is an example of a basic DJ mixer. You need a good pair of headphones to preview any of the inputs. The mixer's master output is connected to the sound system, usually one or more amplifiers that power the speakers. A complete DJ setup will include a monitor near the mixer to hear the overall mix without any of the room delay or echo.