Hello,
Is it possible the snap between shapes to be kept while moving shape. Now, when I move a line for instance after having snapped one point to another line, then only one line moves, not the other one.
Thanks

Welcome to InkscapeForum!

Snapping objects (paths, whatever) together does not make them a single object. They are still unique objects or paths, just sharing the snapping target. Snapping is a tool used to accurately place things. It does not connect them together (like Legos or something). If you want them to move together, there are 3 ways to do it.

1 - Combine paths (Path menu > Combine) -- only works if they are paths, and share the same style (width, color, opacity, etc.). This makes them all subpaths of the same compound path (or iow one path). Not advised if you ever need them to be separate later.
2 - Group (Object menu > Group, or button on Selection tool control bar) -- works on any objects (shape or path) that share a layer. If they are on different layers, grouping will put them all on the same layer. It's easily done and undone. They are still unique objects.
3 - Select both and move them together -- works on any objects, anywhere. They are still unique objects. Without knowing any details about your project, I would suggest this one

thanks Brynn for those detailed explanations !
for my project, well, this is not really clear even to me since I start using Inkscape
I was wondering how modifying an object after having drawn it
for example, if I draw a complex object composed of several lines connected to each other, and then I would like to move only one point to adjust the whole shape, it looks like I will have to move all the lines linked with this point

Ok, well I think you need to know about the Inkscape manual, accessed from the Help menu, with an internet connection. Without an internet connection, Help menu > Tutorials (there are 4 or 5) are excellent for beginners. So you can consult those later. But I'll try to answer for now.

Without seeing your image, or having many details about it, it's hard to know exactly. But it sounds like you must have the endpoints of several paths all snapped together, and occupying the same spot on the canvas. To move all those endpoints together, they need to be all selected. The only way to do that is using the so-called rubberband selection, or also sometimes called a selection box. Anyway, using the Node tool, click and drag diagonally to make an imaginary box around that spot where all the nodes are stacked up on top of each other. (You'll see a dotted line is drawn there as you drag the mouse, so you can see the imaginary box. But as soon as you release the mouse button, that dotted line will disappear.) That will select them all, but of course you can only see the top one that's selected. So while they are all still selected, drag the top node, and all the nodes will move along with it.

If this doesn't entirely solve your problem, please show us a screenshot to illustrate what you want to do. Sometimes it's just impossible to describe certain problems with words, and as they say, "a picture is worth a thousand words"

Sorry for late answer, as you suggested I took time to carrefully read the manual
Selecting stacked nodes of several paths by dragging the mouse was exactly what I was looking for !
Thanks

Wonderful, I'm glad it worked!
And you're welcome