A conjunction is easy to spot in a chart: It is two or more planets situated closely together, generally within an orb of eight degrees. It is one of the major Aspects; neither a hard nor soft energy is specifically ascribed to it.
While conjunctions are often found within the same Sign, they can also fall within adjacent Signs. For example, Mars at 27 degrees Gemini is conjunct Venus at 1 degree Cancer. Here we see an orb of influence of 4 degrees. As with all Aspects, the more exact the angular measurement, or specificity of the orb, the more intense the energy. Therefore, a conjunction at 0 or 1 degrees would be much more powerful than one at 4 degrees.
Conjunctions tend to add great emphasis to the planets and Sign(s) involved. There is no mistaking the effects of a conjunction, for they are palpable and often in full view. Pluto conjunct the Sun can give great intensity and power to the individual, while Mars conjunct Venus can point to an assertive lover. The House in which a conjunction rests is also affected by the presence of neighborly planets. Were the Mars/Venus conjunction noted above in the Fourth House of Home, it could presage domestic battle (or even bliss) between a couple.
The energy of a conjunction can be either favorable or unfavorable, depending on the planets involved. What is important to remember when considering a conjunction is that the tenor of the planets will be enhanced, magnified. This is not likely to be subtle energy.
When three or more planets are in conjunction, a stellium is formed. Again, these planets may fall in the same or adjacent Signs. A stellium has an energy all its own and also greatly influences the Sign and House where it resides.