I often hear from beginners "I'd like to find a pattern for [insert item name here]" not realizing that there can be, for instance, 1000 scarf patterns, yet each of them different. While we utilize patterns to make items, the word pattern is easily thought synonymous with project. However, the word "pattern" also refers to: formally named pattern stitches created by stitch sequence and placement, instantly recognizable pattern styles, and textured stitches that form raised patterns (relief) in the crochet fabric.
1) Pattern stitches (V-Stitch, Shell Stitch, Popcorn Stitch for example). These three pattern stitches are worked into a single stitch or space. Notice the similarities:
V-Stitch: Work 1 dc, 2ch, 1dc into next stitch.
Shell: A number of double or triple crochet worked into one stitch or space.
Popcorn: A number of double or triple crochet stitches worked into one stitch/space, then cinched at the the top so that on the next row, there is only 1 stitch to be worked. see: http://crochet.about.com/library/blpopcrn.htmWork
2) Recognizable Pattern style (Granny Square, Ripple, Round Ripple, Babette to name a few). Once you have started crocheting, there is no mistaking what is meant by these pattern styles.
a) Granny Square*--multilcolored squares, usually joined to make a blanket. While square in shape and worked in rounds, this is nothing but double crochet and chain stitches. *also called a "motif." Varied and abundant motifs can be found in print and on the internet. Thus, a "granny square" could be a new spin on an old favorite.
b) Ripple (or Chevron) resemble horizontal zig-zags created by stitch placement which form peaks and valleys. These can be very pointy and "sharp" or curved and muted. Again, a ripple is comprised of double crochet and chains.
c) Round ripple (ripples worked from the center out in rounds).
d) Babette. A twist on a granny square blanket wherein mismatched sizes of squares are sewn together, usually in wild colors that could only occur in yarn. :) Example here: http://www.interweavestore.com/Crochet/Patterns/Babette-Blanket.html
3) Textural design patterning worked into the project. The best example I can give is the diamond stitch/diamond pattern, an advanced pattern, obviously named for the distinct diamond shapes formed by the exact placement of double crochet stitches worked around the front post of certain double crochet stitches across several rows. It is illustrated at http://www.angelhugs.ca/cs2.html
As such, when deciding what item we'd like to make, we must consider what stitches we want to use...what look or result is being sought...yarn choice, hook size, etc. Those desires influence what ultimately gets produced. The basic stitches (ch, sc, dc, hdc, trc and sl st) are the core of crochet. Once learned, more intricate results are created by following instructions (putting stitches together in sequence and location). I like to call the basics "the alphabets"...how we put them together creates the word, the sentence, the paragraph, the short story, the novel. Be daring, and have fun~!