\documentclass{article} % say
\usepackage{tikz}
\begin{document}
We are working on
\begin{tikzpicture}
  \draw (-1.5,0) -- (1.5,0);
  \draw (0,-1.5) -- (0,1.5);
\end{tikzpicture}.
\end{document}

\tikz \draw (-1.5,0) -- (1.5,0) -- (0,-1.5) -- (0,1.5);

\begin{tikzpicture}
\filldraw [gray] (0,0) circle [radius=2pt]
                 (1,1) circle [radius=2pt]
                 (2,1) circle [radius=2pt]
                 (2,0) circle [radius=2pt];
  \draw (0,0) .. controls (1,1) and (2,1) .. (2,0);
\end{tikzpicture}

\draw (0,0) circle [radius=10pt];
\draw (0,0) ellipse [x radius=20pt, y radius=10pt];
\draw (3mm,0mm) arc [start angle=0, end angle=30, radius=3mm];

\begin{tikzpicture}
  \draw (-1.5,0) -- (1.5,0);
  \draw (0,-1.5) -- (0,1.5);
  \draw (0,0) circle [radius=1cm];
\end{tikzpicture}

\begin{tikzpicture}
  \draw (-1.5,0) -- (1.5,0);
  \draw (0,-1.5) -- (0,1.5);
  \draw (0,0) circle [radius=1cm];
  \draw (0,0) rectangle (0.5,0.5);
  \draw (-0.5,-0.5) rectangle (-1,-1);
\end{tikzpicture}

\begin{tikzpicture}
  \draw (-1.5,0) -- (1.5,0);
  \draw (0,-1.5) -- (0,1.5);
  \draw (0,0) circle [radius=1cm];
  \draw[step=.5cm] (-1.4,-1.4) grid (1.4,1.4);
\end{tikzpicture}

\begin{tikzpicture}
  \draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
  \draw (-1.5,0) -- (1.5,0);
  \draw (0,-1.5) -- (0,1.5);
  \draw (0,0) circle [radius=1cm];
\end{tikzpicture}

\tikzset{help lines/.style={color=blue!50,very thin}}

\begin{tikzpicture}
  [Karl’s grid/.style ={help lines,color=#1!50},
   Karl’s grid/.default=blue]

  \draw[Karl’s grid]     (0,0) grid (1.5,2);
  \draw[Karl’s grid=red] (2,0) grid (3.5,2);
  \end{tikzpicture}

(10pt, 2cm) % 直角坐标
(30:1cm) % 极坐标
+(1cm, 0cm) % 增量坐标，以前一点为基点
++(2cm, 3cm) % 增量坐标，并使新的点成为基点
(<p> |- <q>) % 通过p点的垂线与通过q点的水平线的交点

\path [name path=upward line] (1,0) -- (1,1);
\path [name path=sloped line] (0,0) -- (30:1.5cm); % a bit longer, so that there is an intersection
\draw [name intersections={of=upward line and sloped line, by=x}]
      [very thick,orange] (1,0) -- (x);

\draw[->] (-1.5,0) -- (1.5,0); % 单向箭头
\draw [<->] (0,0) arc [start angle=180, end angle=30, radius=10pt]; % 双向箭头
\draw [<->] (1,0) -- (1.5cm,10pt) -- (2cm,0pt) -- (2.5cm,10pt);

\begin{tikzpicture}[>=Stealth] % 箭头类型为“隐身战机”
\draw [->] (0,0) arc [start angle=180, end angle=30, radius=10pt];
\draw [<<-,very thick] (1,0) -- (1.5cm,10pt) -- (2cm,0pt) -- (2.5cm,10pt); % 末端有两个箭头
\end{tikzpicture}

\begin{tikzpicture}[scale=3] 
  \clip (-0.1,-0.2) rectangle (1.1,0.75); % 裁剪所有后续绘制
  \draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
  \draw (-1.5,0) -- (1.5,0);
  \draw (0,-1.5) -- (0,1.5);
  \draw (0,0) circle [radius=1cm];
  \draw (3mm,0mm) arc [start angle=0, end angle=30, radius=3mm];
\end{tikzpicture}

\begin{tikzpicture}[scale=3]
  \clip[draw] (0.5,0.5) circle (.6cm); % 裁剪区域为圆形
  \draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
  \draw (-1.5,0) -- (1.5,0);
  \draw (0,-1.5) -- (0,1.5);
  \draw (0,0) circle [radius=1cm];
  \draw (3mm,0mm) arc [start angle=0, end angle=30, radius=3mm];
\end{tikzpicture}

\draw (0,0) rectangle (1,1)  (0,0) parabola (1,1);
\draw[x=1pt,y=1pt] (0,0) parabola bend (4,16) (6,12);
\draw[x=1ex,y=1ex] (0,0) sin (1.57,1); 
\draw[x=1.57ex,y=1ex] (0,0) sin (1,1) cos (2,0) sin (3,-1) cos (4,0)
                      (0,1) cos (1,0) sin (2,-1) cos (3,0) sin (4,1);

\fill[green!20!white] (0,0) -- (3mm,0mm)
  arc [start angle=0, end angle=30, radius=3mm] -- (0,0);

\fill[green!20!white] (0,0) -- (3mm,0mm)
  arc [start angle=0, end angle=30, radius=3mm] -- cycle;

\filldraw[fill=green!20!white, draw=green!50!black] (0,0) -- (3mm,0mm)
  arc [start angle=0, end angle=30, radius=3mm] -- cycle;

\shade (0,0) rectangle (2,1)  (3,0.5) circle (.5cm);

\begin{tikzpicture}[rounded corners,ultra thick]
\shade[top color=yellow,bottom color=black] (0,0) rectangle +(2,1);
\shade[left color=yellow,right color=black] (3,0) rectangle +(2,1);
\shadedraw[inner color=yellow,outer color=black,draw=yellow] (6,0) rectangle +(2,1); 
\shade[ball color=green] (9,.5) circle (.5cm);
\end{tikzpicture}

\shadedraw[left color=gray,right color=green, draw=green!50!black]
  (0,0) -- (3mm,0mm)
  arc [start angle=0, end angle=30, radius=3mm] -- cycle;

\begin{tikzpicture}[ultra thick]
  \draw (0,0) -- (0,1);
  \begin{scope}[thin]
    \draw (1,0) -- (1,1);
    \draw (2,0) -- (2,1);
  \end{scope}
  \draw (3,0) -- (3,1);
\end{tikzpicture}

\tikz \draw (0,0) -- (0,0.5) [xshift=2pt] (0,0) -- (0,0.5);

\begin{tikzpicture}[even odd rule,rounded corners=2pt,x=10pt,y=10pt]
  \filldraw[fill=yellow!80!black] (0,0) rectangle (1,1)
    [xshift=5pt,yshift=5pt] (0,0) rectangle (1,1)
           [rotate=30] (-1,-1) rectangle (2,2);
  \end{tikzpicture}

\foreach \x in {1,2,3} {$x =\x$, }

\foreach \x in {-1,-0.5,1}
 \draw[xshift=\x cm] (0pt,-1pt) -- (0pt,1pt);

\foreach \x in {1,...,10}
        \draw (\x,0) circle (0.4cm);

\begin{tikzpicture}
  \foreach \x in {1,2,...,5,7,8,...,12}
    \foreach \y in {1,...,5}
    {
      \draw (\x,\y) +(-.5,-.5) rectangle ++(.5,.5);
      \draw (\x,\y) node{\x,\y};
    }
\end{tikzpicture}

控制文字的位置：